The Right Tools Make a Measurable Difference
Most developers spend more time in their browser than in their code editor. It is where you debug, test, research, review APIs, and check what your work actually looks like to users. Yet many developers use their browser almost entirely out of the box, missing a small set of extensions that meaningfully improve the quality and speed of everyday work.
These five are not trendy or experimental. They are stable, well-maintained, and used daily by working developers across disciplines.
1. JSON Formatter (or JSON Viewer Pro)
If you work with APIs — and virtually every developer does — you will spend a significant portion of your working life looking at raw JSON responses in a browser tab. Unformatted JSON is technically readable. It is also genuinely unpleasant to work with when the response is nested more than two levels deep.
A good JSON formatter extension automatically detects when a browser tab is serving JSON and renders it with syntax highlighting, collapsible nodes, search functionality, and copy buttons. What was an inscrutable wall of text becomes a navigable, scannable structure. The productivity difference on debugging sessions involving complex API responses is immediate and substantial.
JSON Viewer Pro (Chrome) and JSONView (Firefox) are both reliable, lightweight options with no meaningful performance overhead.
2. Wappalyzer
Wappalyzer identifies the technology stack of any website you visit — the CMS, frontend framework, analytics tools, CDN, payment processors, and more. It reads publicly available signals and presents them in a clean popup.
The use cases are numerous: understanding how a competitor built their site, confirming that a library you are considering is used in production by established sites, quickly identifying what framework a job listing's product is built on, or satisfying the universal developer curiosity about what is running under the hood of any interesting product you encounter.
It is genuinely one of the most-used extensions in a working developer's toolkit and requires almost no setup.
3. axe DevTools
Accessibility is not optional — it is a legal requirement in most jurisdictions and a fundamental aspect of building well. axe DevTools is an accessibility testing extension that scans the current page and reports violations against WCAG standards, with clear explanations and links to remediation guidance for each issue.
Running axe on your own work in development is dramatically more efficient than discovering accessibility issues in a QA pass or, worse, a legal complaint. The free version covers the most common and impactful violations. It integrates cleanly with Chrome DevTools and takes less than a minute to run a full audit.
If you build anything user-facing, this extension belongs in your toolkit.
4. ColorZilla
ColorZilla is an eyedropper and colour picker that lets you sample any colour from any element on any page, with the hex, RGB, and HSL values immediately available to copy. It also includes a gradient analyser and a colour history.
The use case sounds narrow — and it would be, if you only needed it occasionally. In practice, front-end developers and designers reach for it multiple times a day: matching a colour from a design that was not documented properly, sampling from a screenshot, checking what colour value a hover state is actually rendering. The time saved across a working week is noticeable.
5. ModHeader
ModHeader lets you add, modify, or remove HTTP request and response headers directly from the browser, without touching your local server configuration. You can set custom headers for specific URL patterns, save multiple header profiles, and switch between them instantly.
The practical applications are wide: testing how your application behaves with different authentication headers, simulating geographic location headers for localisation testing, setting custom user-agent strings, or replicating the header conditions of a specific production environment. For any developer working on authentication flows, API integrations, or environment-specific behaviour, ModHeader is one of those tools that earns its place the first time you actually need it.
A Note on Extension Management
Every extension you install runs code in your browser, with varying levels of access to the pages you visit. A few practices are worth maintaining:
- Only install extensions from the official Chrome Web Store or Firefox Add-ons directory, and check review counts and update frequency.
- Review extension permissions before installing — an extension requesting access to all sites and your clipboard warrants scrutiny.
- Periodically audit your installed extensions and remove anything you no longer use. Browser performance and security both benefit from a lean extension list.
- Use your browser's built-in task manager to check if any extension is consuming disproportionate memory or CPU.
The Common Thread
The extensions above share a few characteristics: they are stable and well-maintained, they serve a clear single purpose, they have minimal performance overhead, and they solve real friction points in everyday development work. That combination — not novelty — is what makes a tool worth installing. Start with one or two that address the problems you encounter most often, and build from there.
