“Free” icons are not all free in the same way. Before you put an icon in a product - especially one you sell - it is worth understanding the licence attached to it. The good news: every icon set in ICON OOP uses a genuinely permissive licence, so the rules are simple. This guide explains them without legal jargon.
Important
This is a plain-language explanation to help you understand the common licences, not formal legal advice. For a high-stakes commercial product, it is always sensible to read the full licence text or check with a professional.
The four licences you will meet in ICON OOP
CC0 - used by Simple Icons
CC0 is as permissive as a licence gets. The creators have effectively placed the work in the public domain. You can use, modify and distribute the files for anything, commercial or not, and you do not even have to credit the source. There are no conditions on the icon files themselves.
MIT - used by Tabler and Phosphor
MIT is a short, friendly licence. You can use the icons in anything, including commercial products, modify them freely, and you do not need to display credit on your website or app. The only formal condition is that the licence text itself should travel with copies of the source files - which matters if you redistribute the raw icon library, but is not something an end user putting an icon on a page needs to worry about.
ISC - used by Lucide
ISC is functionally the same as MIT, just written with fewer words. Same freedoms: commercial use, modification, no credit required on your finished work.
Apache 2.0 - used by Material Symbols
Apache 2.0 is also permissive and allows commercial use and modification. It is a longer licence because it adds explicit wording about patent rights. For the everyday job of using an icon in a design, it behaves just like MIT.
The one real catch: brand logos and trademarks
This is the part that genuinely matters, so read it carefully. The Simple Icons collection contains company and product logos. The CC0 licence covers the icon files - the SVG shapes. It does not override trademark law, which protects the brand itself.
In practice this means:
- Fine: using a company’s logo to link to your profile on that service, to show your product integrates with it, or to reference it accurately.
- Not fine: using a brand’s logo in a way that suggests the brand endorses, sponsors or is affiliated with your product when it is not - or using it as part of your own logo or branding.
The simple test: are you using the logo to refer to that company honestly, or in a way that could make someone think you are that company or are backed by it? The first is fine; the second is not.
Quick reference
| Set | Licence | Commercial use | Credit required |
|---|---|---|---|
| Simple Icons | CC0 | Yes | No |
| Coloured icons | CC0 | Yes | No |
| Lucide | ISC | Yes | No |
| Tabler | MIT | Yes | No* |
| Phosphor | MIT | Yes | No* |
| Material Symbols | Apache 2.0 | Yes | No* |
| Animated icons | MIT | Yes | No |
| Emoji | CC-BY 4.0 | Yes | Yes |
* No credit is needed on your finished website or app. The licence text should be kept with the raw source files if you redistribute the icon library itself.
Emoji: the one set that needs a credit
The emoji in ICON OOP come from Twemoji, the open emoji set originally created by Twitter and now community-maintained. The artwork is licensed under CC-BY 4.0. Unlike the icon sets above, CC-BY does ask for one thing: attribution.
In practice this is simple. If you use Twemoji artwork in a project, include a short credit somewhere reasonable, such as a footer or an about page. A line like “Emoji artwork by Twemoji, licensed under CC-BY 4.0” with a link to the Twemoji project is enough. ICON OOP itself shows exactly that credit in its footer.
This is a light requirement, not a barrier. You can still use the emoji commercially and modify them. You just acknowledge where the artwork came from.
The bottom line
For the vast majority of projects - a website, an app, a client design, a commercial product - the icons in ICON OOP are free to use with no credit required. The two things to remember: treat brand logos with the honesty that trademark law expects, and add a short credit line if you use the emoji.
More questions? The FAQ covers licensing in short form, and the icon sets page describes each collection.