Best Browser DevTools in 2026

Your AI-powered browser for focused deep work

4.3 /5 across G2 and SourceForge · 16 ratings, Jun 2026

Dia is a specialized browser engineered to optimize professional workflows by intelligently organizing information and proactively suggesting relevant content. It acts as a central hub, integrating with various work tools like GSuite, Slack, Notion, and GitHub to provide a unified view of tasks and information. Dia aims to reduce context switching and information overload, allowing users to concentrate on deep work. The browser features include a "Morning Brief" for daily overviews, "Proactive Suggestions" that surface next steps, and an AI-powered search that answers questions by analyzing context across connected applications. It also offers features for better meeting preparation, distinct work and personal profiles, and advanced tab management. Dia prioritizes user privacy with local data storage, end-to-end encryption for synced data, and strict controls over data sharing for product improvement.

An agentic browser that answers questions and takes action across tabs

3.8 /5 across PeerSpot and G2 · 15 ratings, Sep 2026

Comet is Perplexity's AI-powered web browser. It builds Perplexity's answer engine directly into the browser, letting you ask questions about any page, summarize articles, and use an AI assistant that can take actions across your tabs. It is positioned as an agentic browser that completes tasks, not just one that displays pages.

Build, test, and debug APIs faster with a lightweight, open-source API client and web debugger.

4.7 /5 on G2 · 5 ratings, Oct 2026

Requestly is an open-source, lightweight API client and web proxy designed for modern developers to build, test, and debug APIs efficiently. It offers both a browser extension for instant, in-browser functionality and a more powerful desktop application for Mac (with other platforms implied) to handle web, mobile, and desktop app API interactions. Beyond just an API client, Requestly functions as a robust HTTP interceptor and web debugger. It allows developers to intercept and modify network requests, headers, and API responses in real-time. This includes injecting custom scripts (JavaScript/CSS), mocking API responses to build frontends without a backend, simulating edge cases, and redirecting requests. It aims to streamline development workflows by providing a comprehensive tool for API development, testing, and debugging, reducing the need to juggle multiple tools. Requestly also emphasizes collaboration and enterprise-readiness with features like team workspaces, Git synchronization for API collections, role-based access control, and robust security measures including SOC-II compliance, SSO, and data encryption. It positions itself as a powerful, open-source alternative to more 'bloated' closed-source solutions, offering a fast, flexible, and secure environment for API development and debugging.

Solve accessibility issues in web and Windows applications before they reach your customers.

Accessibility Insights is a set of open-source tools designed to help developers find and fix accessibility issues in both web and Windows applications. It offers a browser extension for Chrome and Microsoft Edge, and a desktop application for Windows, enabling comprehensive accessibility testing. The tools are built to integrate seamlessly into development workflows, providing quick checks like FastPass to identify common, high-impact issues within minutes, as well as more in-depth assessment capabilities. It's ideal for developers, QA testers, and anyone involved in building software who wants to ensure their products are inclusive and compliant with accessibility standards like WCAG 2.1 AA.

Boost your website's SEO, speed, and security with comprehensive auditing.

Checkbot is a powerful Chrome extension designed to audit websites for over 50 best practices related to SEO, web speed, and security. It can crawl hundreds of pages in minutes, identifying issues such as broken links, duplicate content, invalid HTML, insecure forms, redirect chains, and more. The tool provides immediate feedback, allowing users to catch critical problems during development before they impact users or search rankings. This tool is ideal for web developers, SEO specialists, product managers, and anyone involved in website optimization. It helps save time on manual testing by effortlessly and reliably checking numerous pages, uncovering hard-to-spot problems that might otherwise be missed. Checkbot also offers in-app guidance to explain identified issues, why they are important, and how to fix them, making it accessible even for those new to website optimization. It supports testing of unlimited sites, including local development and password-protected pages, ensuring continuous website health.

Core performance metrics by Google

Web Vitals measures user experience metrics. Core Web Vitals from Google-the metrics that matter for search and users. The metrics are Google's standard. The measurement is accurate. The optimization is guided. Sites wanting to improve user experience track Web Vitals for Google's key metrics.

Your agentic browser for research, comparison, and output

Opera Neon is Opera's agentic browser. It reads the page, keeps tab and source context, and can research, compare, and produce output you can send. Neon Do runs different agents (agenda, browse, deep research, documents). You can connect existing agents through MCP or CLI. Browser basics stay: tab management, ad blocking, VPN, snapshots. Agentic features and top LLMs unlock at a paid tier after you install and sign in.

AI agents control real browsers via token-efficient ASCII wireframes

Agent Browser enables AI agents to navigate, click, type, and interact with real web browsers using ASCII wireframes, a text-based representation where interactive elements are numbered for efficient token usage. Instead of processing heavy screenshots, AI models receive structured wireframes that maintain semantic clarity while minimizing cost and latency. Built on Playwright, it integrates with MCP clients (Claude Desktop, Cursor), the Vercel AI SDK, and offers an interactive CLI for manual testing.

Modify HTTP request and response headers directly from your browser for web development and debugging.

ModHeader is a popular browser extension designed to help web developers and QA engineers modify HTTP request and response headers. It allows users to easily add, modify, or remove headers such as authorization, set-cookie, and custom headers, directly within their browser. This functionality is crucial for tasks like simulating different user environments, testing API endpoints, debugging web applications, and verifying security policies. The extension streamlines the development workflow by enabling quick changes to header values without needing to alter server-side code or proxy configurations. It's particularly useful for testing various scenarios like different IP addresses, locales, CORS issues, and feature flags. By providing granular control over HTTP headers, ModHeader helps in faster debugging, reducing the time spent on identifying and fixing header-related issues, and ultimately minimizing production bugs. Beyond header modification, ModHeader also offers related tools like a header tester to inspect current request/response headers, and editors for Content-Security-Policy (CSP) and Permissions-Policy headers. These additional tools further empower developers to ensure web application security and functionality.

Unlock Japanese by learning kanji directly from manga and novels through an immersive browser extension.

KanjiLens is a browser extension designed to help Japanese learners master kanji through immersion. It allows users to read their favorite manga and novels online, providing instant kanji lookup by hovering over any character to see its reading and meaning. This eliminates the need to break reading flow for dictionary lookups. The tool also features one-click image translation, utilizing OCR technology to seamlessly translate text within manga panels and other images, making raw Japanese content more accessible. An integrated Spaced Repetition System (SRS) allows users to save new words to personalized flashcard decks, aiding long-term memory retention. Additional features include right-click scanning, custom mnemonics, and customizable settings, making it ideal for anyone looking to learn Japanese by engaging with native content.