Best Browser DevTools Extensions for Web Developers

Browser DevTools are already powerful. But the right extensions can turn them into a specialized development environment — catching accessibility issues, debugging framework-specific state, profiling performance, and inspecting network traffic in ways the built-in tools cannot.

Here are the extensions that genuinely earn their place in a developer's browser.

Framework-Specific DevTools

React Developer Tools

React Developer Tools adds a Components tab and a Profiler tab to your browser DevTools. The Components tab lets you inspect the React component tree, view props and state for any component, and even edit values in real time to test changes.

Why it matters: Without it, debugging React is guesswork. With it, you can trace exactly which component is rendering, what props it received, and what state triggered a re-render.

Key features:

• Component tree inspector with prop and state display
• Highlight updates — see which components re-render on each state change
• Profiler for identifying performance bottlenecks in rendering
• Filter components by name or type

Available for: Chrome, Firefox, Edge.

Vue.js Devtools

Vue Devtools provides similar inspection for Vue applications. Navigate the component tree, inspect reactive state, track events, and analyze Vuex/Pinia store state.

Key features:

• Component inspection with reactive data
• Vuex/Pinia state management visualization
• Event tracking
• Performance timeline
• Router inspection

Available for: Chrome, Firefox, Edge.

Angular DevTools

Angular DevTools lets you explore the Angular component tree and profile change detection cycles. Particularly useful for identifying performance issues caused by excessive change detection.

Available for: Chrome.

Svelte DevTools

For Svelte applications, the Svelte DevTools extension provides component inspection and state management debugging.

Available for: Chrome, Firefox.

Network and API Debugging

JSON Formatter

JSON Formatter automatically formats raw JSON responses in the browser with syntax highlighting, collapsible sections, and clickable URLs. When you open an API endpoint directly in the browser, you get readable output instead of a wall of text.

Why it matters: Simple but saves time every single day. No more piping JSON through jq or pasting into a formatter.

Available for: Chrome, Firefox, Edge.

ModHeader

ModHeader lets you add, modify, or remove HTTP request and response headers without touching your code. Set a custom Authorization header, override Content-Type, add debug headers — all from a toolbar popup.

Use cases:

• Testing API endpoints with different auth tokens
• Simulating CDN headers
• Adding debug flags to requests
• Testing CORS configurations

Available for: Chrome, Firefox, Edge.

Requestly

Requestly intercepts and modifies HTTP requests in the browser. Redirect URLs, modify headers, inject scripts, throttle network speed, and mock API responses — all without changing your backend.

Key features:

• URL redirection (point production API calls to localhost)
• API response mocking
• Request/response header modification
• Network throttling
• Script injection for testing

Pricing: Free tier with core features. Premium plans available.

Available for: Chrome, Firefox, Edge, Safari.

Accessibility

axe DevTools

axe DevTools by Deque is the industry standard for automated accessibility testing. It adds a panel to DevTools that scans the current page for WCAG violations and provides specific, actionable remediation guidance.

Why it matters: Accessibility issues are often invisible to sighted developers. axe catches missing alt text, insufficient color contrast, improper ARIA usage, keyboard navigation problems, and dozens of other issues.

Key features:

• WCAG 2.1 AA/AAA violation detection
• Specific remediation guidance with code examples
• Highlight affected elements on the page
• Save and export reports
• Intelligent Guided Testing for issues automation cannot catch

Pricing: Free browser extension. Pro version adds guided testing and more rules.

Available for: Chrome, Firefox, Edge.

Lighthouse

Lighthouse is built into Chrome DevTools but deserves mention. It audits performance, accessibility, SEO, and best practices in one report. Run it on any page and get scores with specific improvement suggestions.

Tip: Run Lighthouse in Incognito mode to avoid extension interference with results.

WAVE

WAVE by WebAIM provides visual accessibility evaluation directly on the page. Instead of a report panel, it overlays icons on the page showing errors, alerts, features, and structural elements.

Best for: Visual learners who prefer seeing accessibility issues in context rather than reading a list.

Available for: Chrome, Firefox, Edge.

Performance

Web Vitals

Web Vitals by Google displays Core Web Vitals (LCP, FID/INP, CLS) in real time as you browse. The extension shows whether each metric is in the good, needs improvement, or poor range.

Why it matters: Core Web Vitals affect search rankings and user experience. Seeing them in real time during development lets you catch regressions immediately.

Available for: Chrome.

Perfetto UI

For deep performance analysis, Chrome's built-in Performance panel exports trace files that you can open in Perfetto UI for more powerful visualization and analysis. While not an extension, it is an essential companion tool.

CSS and Design

VisBug

VisBug lets you visually edit any webpage — move elements, change colors, modify text, adjust spacing — using design-tool-like interactions. Point, click, and drag to make changes, then inspect the CSS that achieves the result.

Best for: Visual designers who think in pixels rather than code, or developers who want to quickly prototype CSS changes.

Available for: Chrome, Firefox, Edge.

CSS Peeper

CSS Peeper extracts CSS styles, colors, and assets from any webpage in a clean, visual format. Click an element and see its styles presented like a design spec rather than raw DevTools output.

Available for: Chrome.

ColorZilla

ColorZilla is an eyedropper tool that picks colors from any point on a webpage and provides the value in hex, RGB, HSL, and other formats. It also includes a gradient generator and palette viewer.

Available for: Chrome, Firefox.

Productivity

Wappalyzer

Wappalyzer identifies the technologies used on any website — frameworks, CMS, analytics, hosting, and more. Useful for competitive analysis and understanding how other sites are built.

Available for: Chrome, Firefox, Edge.

daily.dev

daily.dev replaces your new tab page with a curated feed of developer news, articles, and discussions. While not a DevTools extension, it keeps you informed about tooling and best practices without subscribing to dozens of newsletters.

Available for: Chrome, Firefox, Edge.

Tips for Managing DevTools Extensions

1. Use profiles. Create separate browser profiles for development and personal browsing. Load DevTools extensions only in your development profile to avoid performance impact during regular browsing.

1. Disable when not in use. Each extension consumes memory and can affect page performance. Disable framework-specific tools when working on a different framework.

1. Update regularly. DevTools extensions need to keep pace with browser updates. Outdated extensions can cause DevTools crashes or incorrect information.

1. Check permissions. Some extensions request broad permissions. Review what each extension can access and consider the security implications.

The Bottom Line

You do not need all of these. Start with the framework DevTools for your stack (React, Vue, Angular), add axe DevTools for accessibility, and pick one or two from the other categories based on your daily pain points. A focused set of well-used extensions beats a toolbar full of tools you never open.