12 Best Chrome Extensions for Web Developers

A few well-chosen Chrome extensions can make everyday web work less fiddly, whether you are learning CSS, maintaining a small business site, or checking a client build. They add tools beside the page you are viewing, so you can inspect details without setting up a separate application for every quick check.

The picks below cover layout inspection, colour and accessibility, performance, and browser testing. Extensions can read sensitive page information depending on their permissions, so install only what you trust, review access requests, and remove tools you no longer use.

Quick picks

• Best for CSS inspection: VisBug — experiment directly with page elements.
• Best for accessibility checks: axe DevTools — surface common accessibility issues.
• Best for responsive previews: Window Resizer — switch among viewport sizes.
• Best for productivity: Wappalyzer — identify technologies behind a site.

How we picked

We selected recognisable tools with a clear development use, prioritising quick checks that complement browser DevTools rather than claiming to replace testing. We considered:

• Usefulness: does it answer a question developers regularly face?
• Trust: is the publisher identifiable and the permission request sensible?
• Ease: can a beginner understand its output?
• Limits: does it explain what it cannot reliably test?
• Cost: are paid features optional or necessary for the task?

Inspect and adjust pages

1. VisBug

VisBug puts visual design controls on top of a live web page, letting you inspect and adjust properties such as spacing, text, and colour while exploring an interface. It is helpful for quick experiments and for showing a designer how a proposed change might feel before editing source files. VisBug is free and open source, but changes are temporary rather than a substitute for making and testing a real code change.

Best for: designers and developers quickly exploring visual alternatives on a page.

2. WhatFont

WhatFont helps identify font families used on a webpage by letting you inspect text in place. That can save time when you are comparing a reference site or checking whether a typography change made it through to production. It is free, but font identification is only a clue: a page may use locally hosted files or fallback fonts, so confirm the actual CSS before drawing conclusions.

Best for: finding the likely typeface behind text in a reference design.

3. ColorZilla

ColorZilla offers an eyedropper for sampling colours from a browser page, alongside colour values and gradient-related utilities. It is convenient when translating a visual reference into a design token or checking a particular border shade. The extension is free, but sampled colour alone does not tell you whether text contrast is readable; verify combinations with an accessibility checker.

Best for: capturing a colour value from a web page for later design work.

4. CSS Peeper

CSS Peeper presents styles and assets from a webpage in a more approachable format than searching through every rule manually. Designers can use it to understand spacing, colours, and images in a reference interface, while developers may find it a quick first pass. It offers free access with paid features; generated observations do not reveal the original design intent or guarantee that a style is reusable.

Best for: designers reviewing visual styling without digging through source files.

Check quality and behaviour

5. axe DevTools

axe DevTools runs accessibility checks against a page and points to issues such as missing names or problematic contrast. Its results give developers a practical starting point for investigation, and the extension is backed by Deque's accessibility work. A free version is available with paid upgrades; automated findings cover only some barriers, so keyboard and assistive-technology testing remain important.

Best for: developers starting an accessibility review of a page.

6. Lighthouse (Chrome DevTools)

Lighthouse is built into Chrome DevTools rather than requiring a separate extension, and audits areas including performance, accessibility, and search readiness. It provides a useful snapshot for a page you are building, with recommendations that can guide the next improvement. It is free, but lab scores vary with conditions and should not be treated as a guarantee of real-user experience.

Best for: getting a repeatable first audit while building a site in Chrome.

7. Web Developer

The Web Developer extension adds menus for tasks such as disabling styles, inspecting images, and viewing page information. Those controls help learners understand how a page behaves when CSS or other features are absent, and can speed up straightforward debugging. It is free; its many functions take time to learn, and it cannot replace testing the actual source or a range of browsers.

Best for: students learning how pages behave when browser features are toggled.

8. Responsive Viewer

Responsive Viewer displays a site across multiple device-sized views at once, making it easier to spot a layout that breaks at a narrow width. It is handy for a quick visual comparison during responsive work, especially before checking real devices. The extension is free, but simulated viewports cannot reproduce every touch, browser, or hardware condition.

Best for: spotting obvious layout differences across several viewport widths.

Workflow helpers

9. Window Resizer

Window Resizer resizes a browser window to common dimensions, helping you reproduce a viewport or check how a page responds as the available space changes. Developers can save time when they need consistent screenshots or quick breakpoint checks. It is free, but a preset window size is only a rough stand-in for a device's full rendering and input behaviour.

Best for: repeating viewport-size checks during front-end development.

10. Wappalyzer

Wappalyzer identifies technologies that may be powering a website, such as content management systems, analytics services, and frameworks. It can help developers understand a site's broad stack or prepare for a migration conversation. The browser extension has free access with paid upgrades; detection is not infallible, and a visible technology guess should not be treated as confirmed infrastructure documentation.

Best for: forming an initial picture of technologies used on a public site.

11. JSON Formatter

JSON Formatter presents JSON responses in a more readable, expandable form when you open them in Chrome. That is useful when checking an API endpoint during development, since nested data is easier to scan than a long unformatted line. It is free; formatting does not validate whether the data is correct or safe, and check the publisher and permissions before installing a similarly named extension.

Best for: making a raw JSON response easier to inspect in a browser tab.

12. ModHeader

ModHeader lets developers modify request and response headers in the browser, a practical aid when testing local or staging behaviour that depends on headers. It can help reproduce a configuration during development without changing application code. A free plan is available with paid upgrades; header changes can affect authentication and caching, so use a clearly labelled profile and disable it when the test is over.

Best for: developers testing how a page behaves with particular HTTP headers.

How to choose the right one

Begin with a specific job rather than installing a bundle of extensions. Use Lighthouse for an initial audit, axe for accessibility findings, and responsive previews to catch layout issues; then confirm important results with manual checks and real devices. For visual references, tools such as VisBug or WhatFont can answer narrow questions quickly, but they do not grant permission to reuse another site's assets or styles.

Check each extension's publisher, recent maintenance, and requested permissions in the Chrome Web Store. An extension that can read data on all websites deserves particular scrutiny; disable it when it is not needed, especially while using banking, client, or admin pages. For image work, Stockio's Base64 image encoder helps convert a small image into an encoded string for testing; use it thoughtfully, since embedding large images can inflate code. Browse Stockio's colour tools for palette tasks and accessibility guides when a quick browser audit needs a more careful follow-up.

Key takeaways

• Keep extensions focused on a real task and remove tools you stop using.
• Check permission requests and the publisher before giving an extension page access.
• Treat automated accessibility and performance results as useful signals, not final proof.
• Test responsive pages on real devices when interaction or critical layouts matter.
• Browser add-ons complement DevTools and sound development practice; they do not replace them.