I've bought icon sets I've never used. I've used free icon sets on projects billed at enterprise rates. I've also ruined a perfectly good product UI by choosing the wrong icon style because I grabbed the first result that came up.
After doing this long enough, here's my honest take: the free vs paid debate in icons is almost entirely the wrong question. The right question is — does this icon set fit the specific visual language your product needs to communicate?
Most designers never ask that question. They just pick what's familiar, or what's trending, or what they downloaded last month. Let me help you ask it better.
The Four Things That Actually Determine Icon Set Quality
1. Optical consistency across sizes.
An icon that looks crisp at 24px can look muddy at 16px and overweight at 32px. Before committing to any icon set — free or paid — test it at every size you'll actually use. Not just the hero size. The smallest size you'll ever render it at.
2. Stroke consistency.
In outline-style icon sets, every icon should use the same stroke width. When you put icons from two different sets next to each other, the inconsistency becomes immediately apparent, even to non-designers. One icon at 1.5px stroke next to another at 2px stroke looks broken.
3. Conceptual clarity.
The icon should be immediately understood without a label. If you need to hover over it to know what it does, it's a bad icon regardless of how beautiful it looks. This is harder to judge from a preview page — download the set and put icons in actual UI context to evaluate it properly.
4. License clarity.
"Free" is not a license. MIT is a license. OFL is a license. CC0 is a license. Always read the actual license before using any icon set in commercial work. This is not pedantic — it protects you and your clients.
The Icon Sets Worth Your Time
Phosphor Icons — My Default for Everything
6 styles. 1,200+ icons. Free for commercial use. No attribution required.
This is the icon set I install first on every project and only replace when there's a specific reason to. Here's why: the multi-style system solves the problem of needing icons that feel different across different surfaces of your product.
Use Regular weight in your application UI. Use Bold weight in your empty states and onboarding illustrations. Use Duotone for your marketing page feature sections. It's the same icon library, but the style variation gives each surface the right visual weight.
The quality of Phosphor is exceptional. The icons are drawn on a proper grid, with optical corrections made by hand, with a consistent philosophy about simplification. You can feel the craft.
What I actually use it for: web applications, SaaS products, developer tools, design tools. Almost everything.
The one situation where I don't reach for it: when a client has an existing brand icon system that doesn't match Phosphor's geometric style. In that case, consistency with the existing brand beats quality of the new resource.
View Phosphor Icons on Mantlr →
Heroicons — The Tailwind Designer's Icon Set
292 icons. Outline and solid styles. Designed by the Tailwind CSS team.
I want to be clear about what makes Heroicons special, because it's not what most articles say.
Most coverage focuses on the quality and the clean design. Those things are true. But the real reason Heroicons matters is the intent behind each icon. These 292 icons were chosen because they represent the 292 things you actually need to communicate in a web application. No filler. No icons for obscure use cases. Every single icon earns its place.
Steve Schoger's optical precision is visible throughout. The circle on the search icon is positioned so it reads as search, not as a circle with a handle. The chevron directions are deliberate. The difference between a filled heart and an outline heart communicates exactly what it should.
What I actually use it for: Tailwind CSS projects specifically, because the design language matches what Tailwind developers naturally build. Also for any project where 292 icons is genuinely enough — which is more projects than you'd think.
The limitation: 292 icons is a real ceiling. If your application has complex feature areas with many distinct concepts, you will hit gaps. Have a plan.
Tabler Icons — When Coverage Is the Requirement
4,200+ icons. Consistent outline style (1.5px stroke, rounded caps). Free and open source under MIT license.
There's a type of project where Tabler is the only honest answer: enterprise applications with extensive feature sets where you need an icon for everything. Content management systems. ERP dashboards. Healthcare platforms. Analytics tools where 50 different chart types each need their own icon.
At 4,200+ icons, you will find what you need. The MIT license means you can use it in anything. The Figma plugin is well-maintained and makes finding specific icons fast.
The honest limitation: with 4,200 icons, quality control becomes difficult at the edges. The common icons (home, settings, user, search, chevrons, close) are excellent. Some of the more obscure icons — specific file format icons, industry-specific symbols — are less refined. Spot-check before using any icon you haven't seen in production before.
What I actually use it for: internal tools, admin dashboards, enterprise software, anything where I'd rather over-prepare for icon needs than under-prepare.
Lucide — The React Developer's Choice
Community-maintained fork of Feather Icons. 1,000+ icons. Tree-shakeable React package.
The reason Lucide exists is worth understanding: Feather Icons was beautiful but unmaintained. The community forked it, maintained it, expanded it, and built a first-class React package around it. The result is a library with Feather's elegance plus the coverage and developer experience that Feather never had.
The React package is what makes Lucide genuinely excellent. It's tree-shakeable (only the icons you use make it into your bundle), fully typed (TypeScript autocomplete for icon names), and consistently updated.
What I actually use it for: React and Next.js applications where I'm writing code alongside designing. The developer experience is exceptional and the visual quality is consistently good.
Solar Icons — For Marketing, Not UI
7,500+ icons across 6 styles. The Duotone variant is the reason to be here.
Let me be direct: I don't use Solar in application UI. The duotone style — where icons use two complementary colors to create depth — is too expressive and too visually heavy for interface icons. In a nav sidebar or a toolbar, Solar Duotone would pull attention away from the content.
But on a marketing landing page? On a feature section explaining what your product does? On an onboarding slide deck? Solar Duotone adds visual richness that makes flat content sections come alive.
The discipline is keeping it out of your UI and using it only on marketing surfaces. That boundary matters.
The Decision Framework I Actually Use
Web application: Phosphor Regular weight. Phosphor Bold for empty states.
Tailwind project: Heroicons, supplemented by Phosphor for anything Heroicons doesn't cover.
Enterprise application: Tabler for coverage, Phosphor for the most prominent UI icons.
React application: Lucide for the developer experience.
Marketing pages alongside any of the above: Solar Duotone for feature sections, Phosphor for UI-adjacent elements.
The Mistake That Costs the Most Time
Mixing icon sets within a single product surface.
I've reviewed designs where the navigation used Heroicons, the dashboard used Lucide, and the settings page used Tabler. Each set individually was good. Together they looked incoherent — different stroke weights, different geometric philosophies, different levels of detail.
Pick one icon set per product. If you need to switch for a specific use case (like Solar for your marketing page), keep the boundary clean. Mixed icon sets read as mistakes even to users who can't articulate why.