Best monday.com Alternatives in 2023

If you're looking for a monday.com alternative, Teamwork is the best option available. It's a better project management software overall, with more tools for managing tasks and projects as well as better customer support options for when you get stuck. Plan-by-plan, Teamwork is cheaper than monday.com and better value for money. Overall it scores 4.6/5, while monday.com scores 4.7/5.

However, Teamwork is not the only monday.com alternative – you'll actually get a broader range of features in ClickUp. There are 15 different “views” you can use to track the progress of your project, such as a Gantt chart, which means you'll save time you currently spend chasing things up or requesting updates. If you're managing complex, data-heavy projects, you'll find ClickUp's powerful features more capable than monday.com's.

If you're a dedicated Excel or Google Sheets user on the other hand, you might prefer a provider like Smartsheet. It provides a spreadsheet-style default interface that you may find makes your transition to project management software a little simpler. In this guide, we cover:

• Best monday.com Alternatives: Table
• Best monday.com Alternatives: ClickUp, Smartsheet, Wrike and More
• Should you Choose monday.com Anyway?
• Best Free Alternatives to monday.com
• Our Research and Methodology
• Verdict: The Best monday.com Alternative
  
• Frequently Asked Questions

Best monday.com Alternatives: Table

Scroll down for detailed reviews of the best monday.com alternatives to see how their pricing and plans compare to monday.com. If you don't have the time, don't worry – check out the table just below for a whistlestop comparison:

Best monday.com Alternatives: Compared

monday.com is a great project management system, but that it doesn't mean that it's the best project management system for your business. While it still ranks high in all of our testing, these popular management tools may be a suitable alternative.

1. Teamwork (4.6/5) – Best monday.com alternative
2. ClickUp (4.5/5) – Best for task management and collaboration
3. Asana (4.5/5) – Best for displaying project data
4. Wrike (4.4/5) – Best for integrations
5. Trello (4.3/5) – Best for customer support
6. Smartsheet (4.2/5) – Best overall for spreadsheet users

1. Teamwork

Our research suggests Teamwork is the best monday.com alternative overall, boasting high scores in our ease of use tests (4.3/5) task management (4.3/5), and security (5/5), while undercutting much of the market when it comes to pricing.

• Best monday.com alternative: Overall
• Price from: $5.99 per user, per month
• Free plan? Yes.

Teamwork overview

Teamwork is an excellent all-rounder, scoring 4.6/5 overall. It scores 4.2/5 for workflow creation, thanks to an automation builder on all plans and a solid range of preset project templates to choose from based on different organizational departments. It's only bettered by ClickUp, Wrike, and monday.com when it comes to task management, scoring a very respectable 4.3/5.

One of the best things about Teamwork is how many of those task management features are included on its free plan. There's a Gantt chart, Team view, task dependencies feature, and a Calendar view, none of which are included in monday.com's free plan.

Teamwork performed really well on our ease-of-use tests – aside from monday.com, it's the most intuitive and usable program we've tried, scoring 4.3/5. Our testing group found it really easy to transition between views, build up a dashboard of data, and extract insights that revealed how our test projects were progressing. The automation builder was also much easier to master than Wrike's, ClickUp's, and Asana's.

There's also a chat function that's an add-on for Teamwork's Free Forever and Starter plan but it's built-in to the pricier plans, which not a lot of project management tools offer. There's also a document editing tool that you can use to annotate documents and comments, which providers like Asana don't offer.

Teamwork pricing vs monday.com pricing

Teamwork is better value for money than monday.com, scoring 4.4/5 for pricing compared to monday.com's 3.9/5. Teamwork and monday.com both have a paid plan, but its first plan, the Starter plan ($5.99 per user, per month), is cheaper than monday.com's Basic Projects plan.

The Deliver plan is virtually the same price ($9.99 per user, per month) as monday.com's Standard Projects plan ($10 per user, per month), as is the Grow plan ($19.99 per user, per month) and monday.com's Pro Projects plan ($19 per user, per month).

Having reviewed all of the features on all of these plans, it's clear Teamwork offers more features, earlier on in its pricing structure than monday.com. As we mentioned above, the free plan is a lot better than monday.com's free plan.

Check out our full guide to Teamwork pricing for more information.

Is Teamwork better than monday.com?

Although it's better value for money if you look at the software side by side, monday.com is the better piece of software. It's easier to use and has a more minimalistic layout, and it's got better task management features on the Standard and Pro project plans.

monday.com also scores 5/5 for data visualization, and although displaying data from our mock projects was easy with Teamwork, monday.com made it even easier, and the dashboard where you keep your widgets and charts is a little clearer and customizable. The two providers' automation builders were the two easiest to use, too – monday.com's text-based system is really simple to understand, which can't be said for all the monday.com alternatives featured in this article.

The bottom line is that monday.com excels in many of the same areas that Teamwork does – it's just that little bit better overall, and that's probably why it's that little bit more expensive too.

2. ClickUp

Our research suggests ClickUp is the second-best monday.com alternative overall, and the best project management software for task management (4.7/5), collaboration (4.7/5), and overall functionality (4.6/5), while undercutting the rest of the market when it comes to pricing.

• Best monday.com alternative for: Task management and collaboration
• Price from: $7 per user, per month
• Free plan? Yes.

ClickUp overview

Created in 2016, ClickUp hasn't been around as long as its rival monday.com, but its impact on the business software market is big and growing. Similar to monday.com, however, ClickUp depicts itself as far more than a task management dashboard. In fact, its celebrated software platform ‘work operating system (OS)', which lets all employees organize their schedules around one central point, is one of the highest-rated remote tools in the business world.

One of ClickUp's most distinctive features is its multiple views function, which lets users view their projects in multiple different ways, including in list, board, and calendar formats. The software also offers a time tracking feature on its business plan, unlike monday.com which only features the tool in its premium package. This makes ClickUp a better solution for project managers looking to account for their time and helped the provider to a better task management score (4.7/5) than monday.com (4.5/5).

ClickUp even offers burndown charts for scrum teams and a team instant messenger for collaboration, both of which monday.com does not offer. If, like many Agile teams, you're looking for a flexible, contemporary monday.com alternative that can adapt to the needs of both your project and methodology, look no further than ClickUp.

ClickUp pricing vs monday.com pricing

ClickUp's raft of features and generous free plan make it better value for money than monday.com overall, scoring 4.4/5 for pricing compared to monday.com's 3.9/5. Although monday.com is good value-for-money compared to most of the rest of the market, ClickUp is really cheap.

Both providers offer a free plan, but ClickUp's free plan is much more comprehensive. Not only does it have an unlimited user limit (which monday.com doesn't), but it also welcomes salesforce CRM add-ons. In fact, aside from Teamwork, ClickUp has the best free plan available. The only key difference is that ClickUp puts limits on how many times you can some features, like its Gantt chart.

Across the board, ClickUp is priced much more affordably than monday.com. ClickUp's first paid plan is just $5 per user, per month, the same as Trello's, whereas monday.com's first paid plan is more expensive than both at $8 per user, per month. It's also cheaper than monday.com's Standard plan, which comes in at $10 per user, per month.

This trend continues, with ClickUp's business plan coming in at just £12 per user, per month compared to monday.com's Pro plan at $16 per user, per month. ClickUp also offers an additional Business plan, the Business Plus plan ($19 per user, per month) if you want more advanced features designed for multiple teams working on the same projects.

Read our ClickUp pricing and monday.com pricing pages for more information on these providers.

Is ClickUp better than monday.com?

It's fair to say that monday.com and ClickUp are some of the biggest names in business software, so choosing between the two was never going to be easy. Our research team thought monday.com (4.7/5) edged it overall when put up against ClickUp (4.5/5) – but it was incredibly close.

While monday.com is one of the best solutions on the market, our research indicates that ClickUp is slightly better value for money. ClickUp's first paid plan is much cheaper than monday.com's first paid offering ($7 per user, per month vs $8 per user, per month), and it offers a free plan with more features like Gantt charts and no user limit, whereas monday.com's no-fee offering doesn't.

The key thing to remember is that you get more features for less money with ClickUp, whereas monday.com locks more away on expensive plans. monday.com, however, has 24/7 hour live support and live chat features (monday.com achieved a customer support score of just 4.5/5  compared to ClickUp's 3.3/5), as well as a tidier interface and generous storage limits. ClickUp's interface might not be as easy as monday.com's to use, but its bountiful software integrations and useful tools firmly more than help it keep pace with our top-rated provider.

3. Asana

Asana has a clean, tidy user interface, so we'd recommend it for beginners who still want a hefty amount of features to work with once they wrap their heads around the software. Granted, Asana is on the pricier side, but its dashboard view is really useful for finding out how your project is progressing and aside from Teamwork and monday.com, it's the easiest software to use.

• Best monday.com alternative for: Displaying project data
• Price from: $10.99 per user, per month.
• Free plan? Yes.

Asana scores 4.3/5 for task management, with its Gantt-chart-like project schedule and a variety of additional views that are available on all of its plans. It's got all of the same features as monday.com aside from an AI assistant that can turn text into action items, which is why monday.com scores slightly higher (4.5/5) for this assessment area.

Katie is an SEO Campaign Executive who'd never used Asana until her current manager installed it for her team, and she really enjoys how easy the custom fields feature is to use. “You can add custom fields on tasks, so for our commercial link tasks I added fields for the brief, the article, the live link, the brand, and the date live,” she said.

Despite its impressive 4.2/5 score on our ease of use tests, not everyone in our testing group liked Asana. “It felt a little bit cramped to me because there's a lot of data in there,” software researcher Ollie Simpson explained during Tech.co's recent project management platform tests. “I didn't feel like I had that much space to scroll”. monday.com, on the other hand, was praised for its clever use of white space and minimalist approach.

Although monday.com scored 5/5 for data visualization during our recent testing series thanks to its broad selection of widgets and charts, Asana's lucid displays do arguably give the project management giant a run for its money, helping it to a 4.8/5 in this assessment area.

Unfortunately, Asana doesn't come for cheap, and unlike Teamwork's free plan, its free plan is very limited, with no data visualization tools included. So let's see how its price measures up to monday.com's next.

Asana pricing vs monday.com pricing

The aforementioned Asana free plan, Asana Basic, does not demand a fee but also does not give away too many features, such as the provider's excellent automation builder. With no data visualization tools and substandard customer support, it definitely falls short of monday.com's free version.

Asana's cheapest paid plan, on the other hand, will cost you $10.99 per user, per month, with the Business plan costing starting from $24.99 per user, per month. Compared to monday.com's prices this is a little steep – monday.com's first paid plan, the Basic Projects plan is just $8 per user, per month.

But in fairness to Asana, you do get more bang for your buck than you would with monday.com's comparable Basic Projects plan, as it has more data tools and pre-built automations. However, monday.com's fully-featured Pro Projects plan, the provider's most expensive plan with public pricing, is just $19 per user, per month, which is much cheaper than Asana's Business package.

Both providers offer Enterprise plans geared towards larger businesses, but you'll have to contact their respective sales teams for more information on getting a quote for your business.

Is Asana better than monday.com?

In short, we don't think Asana's project management software tops monday.com's. But that isn't to say it's without its strengths. Asana's software is extremely easy to use and visually compelling, so will definitely be an asset to many businesses.

However, businesses will end up paying a lot more for Asana than monday.com if they really want project management software that can handle multiple teams, projects, and complex tasks sufficiently – and monday.com's Pro Projects is both cheaper and more usable.

4. Wrike

Wrike can cover almost all of your project management needs, and is an excellent choice for large businesses orchestrating data-intensive projects involving multiple teams, staff members, and software applications. Wrike scores 4.7/5 for task management, improving on its 2022 score (4.6/5) and beating monday.com (4.5/5) in that category.

• Best monday.com alternative for: Complex task management
• Price from: $9.80 per user, per month.
• Free plan? Yes.

Wrike overview

Wrike‘s suite of task management features also makes it particularly an effective tool for users handling large or complex projects. Wrike scores 4.7/5 for task management compared to monday.com's 4.5/5, thanks largely to a much more useful employee capacity management tool. Wrike is relatively easy to use, and deploys a three-pane layout. However, like Asana, it can start to feel a little cluttered and cramped – but there's a way around that.

“One thing that hugely improved my experience of Wrike was hiding a sidebar. I don't know why, but the sidebar just really bothered me. It just felt like it was squeezing things too much and making things incredibly small,” said Tech.co's lead software researcher James Macey, who participated in our project management testing series.

However, Wrike's automation builder is a lot clunkier than monday.com's, which helped it edge Wrike on our ease-of-use tests, scoring 4.5/5 to Wrike's 4.1/5. When I was testing Wrike to build automations, it didn't seem like there was a way to set a trigger around the assigning of tasks (if there was, it definitely wasn't clear) – and I thought this would be a basic style of automation that would be worth including.

Wrike scores decently for data visualization (3.8/5), with 5 different available chart types and 15 widgets. Integrations are another strong point, with Wrike offering a much wider range of marketing and financial integrations than the other providers on this list. It also integrates with business comms platforms like Slack, Teams, Zoom, and RingCentral.

Wrike pricing vs monday.com pricing

Unfortunately, Wrike's feature-rich software comes at a slightly heavier price tag than monday.com, making it one of the more expensive monday.com alternatives. Wrike's cheapest plan is available at $9.80, per user, per month – which is slightly more expensive than monday.com's $8 per user, per month Basic package.

Wrike's next plan, the $24.90 per user, per month Business plan, is a lot more expensive than monday.com's Pro projects plan ($16 per user, per month). However, monday.com also has the Standard plan ($10 per user, per month), so if you're a smaller business that doesn't like the look of that hefty Wrike Business package price tag, we'd consider taking a look at the cheaper plans on offer from monday.com.

For users with more limited management needs, however, Wrike does offer a free plan. With an unlimited project limit and generous storage capacities, this complementary plan might just take the edge over monday.com's, which has a user limit of 2 and omits several core features.

Learn more about Wrike's pricing plans here.

Is Wrike better than monday.com?

There's no denying it, Wrike is a really promising project management solution, especially if you're looking to manage complex, data-intensive tasks that need to be accessed by a variety of individuals or teams. monday.com, however, is better overall, scoring 4.7/5 compared to Wrike's 4.5/5, and the customizable platform will suit a wider range of businesses.

We used to recommend Wrike for businesses that specialize in marketing or professional services, thanks to plans geared specifically towards these types of teams. However, Wrike recently discontinued its Marketing and Professional Services plans – although it still has many features these sorts of teams would find useful, like tools for visualizing data.

If you're serious about finding a free solution, Wrike's complementary plan might also come up on top of monday.com's. With no user limits, effective data visualization tools, and limitless integrations, it definitely ranks competitively against monday.com, which has a user limit of 2 on its free plan.

Overall though, monday.com's paid plans are easier to use and generally provide more bang for your buck.  Therefore, for small-to-medium-sized businesses with standard project management needs, we still think monday's software comes out on top. For bigger businesses that need advanced tools for complex projects – and have that bit more budget to spend – Wrike can definitely be taken into consideration.

5. Trello

Trello scores 4.3/5, putting it in the middle of the pack. It's a more limited monday.com alternative than Wrike, Asana, ClickUp, and other competitors, but if you're looking for a simple way to get your team more organized and don't want to be overwhelmed with features, Trello should be your go-to.

• Best monday.com alternative for: Customer support, basic task management
• Price from: $5 per user, per month.
• Free plan? Yes.

Trello overview

With an intuitive automation builder and a simple, uncrowded interface, Trello is another great option for small to medium-sized teams. Much like monday.com's offering, the software is clean and visually appealing, making creating and managing tasks a breeze. Trello works by letting you organize your projects into customizable boards.

While this layout caterers well to smaller-scale projects, if you're managing multiple teams and are looking to scale, this software won't be for you. Trello scores just 2.9/5 for task management and doesn't include key features like task dependencies, whereas monday.com does.

However, Trello only scores 4.1/5 on our ease of use tests compared to monday.com's 4.5/5 – although they're both quite easy to use, Trello is more limited and basic, so you won't be able to do as much with it as you can with monday.com.

One area where Trello does beat monday.com is customer support. On Trello's Enterprise plan (which is around the same price as monday.com's Pro Projects plan) you'll have access to 24/7 support and you'll be able to contact the provider by phone, email and live chat too.

Trello pricing vs monday.com pricing

While it might not work for every team, Trello's prices can't be beaten. It scores 4.4/5 for pricing compared to monday.com's 3.9/5, largely because it's so affordable.

Trello's Standard plan costs $5 per user per month, its premium costs $10 per user per month, and its enterprise stands at a fixed price of $17.50 per user per month. It even offers a free tier with no limit on users, storage, or integrations.

Trello's Premium plan is the same price as monday.com's second paid plan, the Standard plan ($10 per user, per month), and its Enterprise plan is one of the only Enterprise plans with public pricing (monday.com's, by comparison, has no public pricing).

Is Trello better than monday.com?

For smaller teams looking for no-frills, cost-effective project management software, Trello could serve you well. The software's limited storage options and lack of collaboration features and data visualization tools do, however, make it inadequate for users managing larger, more complex projects. Because Trello isn't a great fit for all businesses, we can't position the tool above monday.com's all-rounded offering.

6. Smartsheet

Spreadsheet users, rejoice. SmartSheet is undoubtedly the best project management software for spreadsheet loyalists – Excel and Google Sheets users alike.

• Best monday.com alternative for: Spreadsheet fans
• Price from: $7 per user, per month.
• Free plan? Yes.

Smartsheet overview

Ultimately, Smartsheet is like an extremely advanced spreadsheet tool packed full of project management features. It helps workers track and manage projects easily, and uses an interface that isn't too different from a spreadsheet itself. It also makes it super easy for project managers to automate processes and keep their data secure.

Even if you don't rely on spreadsheets to carry out business activities, Smartsheet is easy enough to set up and use. Unlike monday.com, however, which uses the Kanban board to display and visualize tasks, Smartsheet's default layout makes it quite hard for workers to analyze their workload at a glance. But have no fear, Kanban boards are available in Smartsheet, as well as a Gantt chart view, so you can choose what suits your team.

Smartsheet's 4.4/5 score for security is thanks in part to its broad range of compliance certifications and the sign-in options on the Enterprise plan. Its customer support score of 4.5/5 is higher than ClickUp's and the same as monday.com's – although you do have to pay a fee for some services, such as onboarding.

Smartsheet Pricing vs monday.com pricing

In terms of cost, monday.com will be your best bet. SmartSheet offers a free plan that's quite similar to monday.com's, although its Pro plan is $7 per user, per month, slightly cheaper than monday.com's Basic Projects plan ($8 per user, per month). Smartsheet's plan is the better one too, with more features including a calendar, automations, and task dependencies, which monday.com's Basic projects plan doesn't offer.

However, the third and final pricing plan in Smartsheet's pricing structure, the Business plan, is $25 per user, per month, considerably more than monday.com's Pro plan ($16 per user, per month). As you can see, if you're after a basic package, the provider does offer a reasonable plan roughly around the same price as monday.com. But in terms of overall affordability, monday.com definitely takes the crown.

Is Smartsheet better than monday.com?

If it's spreadsheet compatibility you're after, StartSheet might be a strong monday.com alternative for you. As we've covered, it's the more usable program overall if you stick with it, and you're less likely to feel like you've been chucked in at the deep end than you might initially with monday.com. If spreadsheets are your comfort zone, you should definitely opt for Smartsheet.

In comparison to other providers, Smartsheet didn't perform as well as it did last year. A good example is our ease of use tests. Project management software like Wrike, Asana, and Teamwork are all very similar and take quite an intuitive approach – monday.com, on the other hand, is a lot more minimalist. In Smartsheet, I felt a little lost at first – it definitely took a while longer to get to grips with.

However, due to Smartsheet's expensive paid plans and infrequent opportunities to customize the product, we think monday.com's software is better for businesses overall. Once you get used to monday.com, you'll find the user interface easier to navigate and use than both Smartsheet and traditional spreadsheets.

If you're looking for an even more comprehensive comparison, check out our guide to the two options, Smartsheet vs. monday.com.

Should You Choose monday.com Anyway?

As you can see, the market isn't short of great project management tools. But while monday.com's competitors all bring something unique to the table, the provider is one of the leading names in the industry – and for good reason too.

Unlike some project management solutions, monday.com can be used by just about any business. This is because the offering is well-rounded and offers lots of customization options that other providers don't.

monday.com scores 4.5/5 for task management, with a Gantt chart, spreadsheet view, and Kanban board all provided – although Kat, an editorial assistant who uses monday.com, said they didn't find the Kanban very useful “until more step-by-step like tasks have been added on the main tabs”. monday.com also scores 3.8/5 for project and workflow creation, thanks to a huge range of preset project templates that will suit a variety of different teams.

“It felt more like it had been tested more times and troubleshooted more than other platforms,” remarked Alice Martin, a business writer who participated in our project management user testing series. “Everything is placed very intuitively. It feels kind of like an apple product in the way of like you just instinctively knew how to work it.”

With monday.com, there are multiple ways to view project progress and manage tasks, but the provider retains an easy-to-use interface to ensure monday is suitable for experienced project managers and beginners alike.

Aside from its impressive versatility, monday.com's raft of useful tools is another thing that separates it from its competition. For instance, while many project management solutions lack basic communication tools, monday.com's Collaborative Whiteboard feature really goes above and beyond.

It gives teams a place to sketch and type ideas for each other in real time, making remote collaboration easier than ever. In fact, monday.com scores 3.8/5 for collaboration, which was the third-highest score achieved by a provider on our last round of testing. However, it's worth saying that competitors like ClickUp now also offers an online whiteboard and go further with things like a team instant messenger, which was added last year.

Despite monday.com's wealth of offerings, if you find yourself in hot water, the provider isn't easy to reach. With no live chat option, no customer service helpline, and no 24/7 support, monday doesn't cater to customers looking for on-demand help and feedback. If this is a dealbreaker for you, it's probably better to opt for a solution with better support options, like ClickUp.

All things considered, we still think monday.com's affordable pricing tiers, excellent task management features, and potential to be customized make it a solid option for most teams. You can learn more about monday.com's pricing structure in the table below. If you'd like more information about monday.com's features, check out our monday.com review.

The Best Free monday.com Alternatives

Paid tools will always edge out free versions, but monthly fees aren't conducive to every business' budget. Fortunately, monday.com's free plan – which is quite limited compared to competitors' free offerings – isn't the only option out there. The issue with monday.com's free plan is the user limit of 2, which makes it unsuitable for even most small teams.

Teamwork has one of the best free plans on the project management software market. Unlike monday.com's plan, Teamwork provides a Gantt chart, phone-based support, and custom automation on its free plan. It's much more fully-featured and although it also has a restrictive user cap, it's a better choice than monday.com's.

Wrike's free plan is another serious contender. Also offering an unlimited user and project limit and seamless integrations with Slack and Microsoft Teams, businesses on the hunt for effective free software shouldn't look past this offering. Unfortunately though, Wrike's free plan is lacking data visualization tools and some basic customer support functions, so it isn't going to work for everyone.

Truth be told, Jira's free service also blows monday.com's out of the water. Unlike monday.com, businesses using Jira's free plan aren't restricted by project or user limits. This gives you unlimited scope to use the software across your business. There are other features Jira free plan includes that monday.com's doesn't, such as preset and custom charts for displaying data. overall, it's a better program to not spend anything on.

Executing a project from start to finish doesn't come cheap. By using free project management tools you're able to funnel these savings into other areas of your business. However, while free and ‘freemium' tools can help businesses to save money initially, they can often end up costing you more in the long run. This is because they usually lack the features your business will need to make bigger, longer-term savings.

About Our Research: How We Ranked monday.com Alternatives

Here at Tech.co, we spend time conducting data-driven research into all of the services and software that we review and compare – including all the monday.com alternatives featured in this article (and monday.com too!).

We award each product multiple scores depending on how well they fare in a variety of carefully constructed testing environments. The assessment areas we focus on are selected based on common small business priorities and considerations that our readers have shared.

Project management software testing criteria

Before testing our top monday.com alternatives, our insights team spoke to a number of businesses that work regularly on projects. Then, they created a research framework to use to assess providers based on the wants and needs of these businesses. The four core areas of inquiry our team focused on included:

• Price – is the product good value for money, considering the price point against the features on offer?
• Ease of Use – how easy is the product to use, and how big is the range of tasks it can complete? Is it difficult or easy to set up when you're starting out, and how much help does the user get during this process?
• Functionality – what features are offered by the provider, and how do they fare during a rigorous usability test? Task management, workflow creation, data visualization, and collaboration features were used as sub-categories.
• Customer support – what customer support options are available, and do they work well?
• Security – what security options does the provider offer? Is two-factor authentication provided?
• Integrations – what other software applications does the platform connect to?

Tech.co does have commercial partnerships with some of the providers we write about, but importantly, our research team's findings allow us to stay editorially independent. If we don't have the results and the data on a product, we don't write about it.

Frequently Asked Questions