Debugging a broken payload in the network tab used to mean copying JSON into ChatGPT, pasting the error back, and rebuilding context. A new class of browser extensions cuts that loop entirely: they read the DOM, watch DevTools output, and answer questions inside the same window. Here are seven AI web debugging extensions worth installing on desktop in 2026.
What to look for
Before picking an extension, check for four things:
- DevTools access. Can it see the network tab, console, and inspected element, or does it only read the visible page?
- Model routing. Is it locked to one model or does it let you pick between Claude, GPT-5, and Gemini per task?
- Local mode. Can it be pointed at a local LLM server (Ollama, Jan, LM Studio) for private codebases?
- Prompt library. Are debugging prompts saved and shareable across sessions?
Quick comparison
| App | Best for | Platforms | Free plan | Starting price/mo | Rating |
|---|---|---|---|---|---|
| Claude for Chrome | Deep debugging with a long-context model | Chrome, Arc | Free with Pro subscription | Pro $20 | 4.7 |
| GitHub Copilot Chat | Reading repo context in the browser | Chrome, Edge | Free tier included | Copilot Pro $10 | 4.5 |
| Sider Fusion | Fast general assistant with multi-model | Chrome, Edge | Free tier | Pro $10 | 4.6 |
| Monica | Sidebar chat plus writing tools | Chrome, Edge, Firefox | Free with cap | Pro $8.30 | 4.5 |
| Merlin | Everyday research and coding help | Chrome, Edge | Free tier | Pro $19 | 4.4 |
| HARPA AI | Web automation and monitoring | Chrome, Edge | Free with cap | Premium $19 | 4.3 |
| Perplexity Companion | Cited answers in a sidebar | Chrome, Edge, Firefox | Free | Pro $20 | 4.5 |
The extensions
1. Claude for Chrome – Best for deep debugging
Claude for Chrome is the extension that pushed the category forward. It reads DevTools output, follows page state, and can execute actions on the tab. The 200k-token context window means a stack trace plus the network payload plus the offending function all fit in one turn.
Where it falls short: Availability rolls out in waves and requires a Claude Pro or Max subscription during preview. The action mode still asks for confirmation on every click.
Pricing:
- Free: base subscription-gated, limited to Claude Pro members
- Paid: Pro at $20/mo, Max at $200/mo
- vs standalone Claude: same model, wired into the browser instead of a chat window
Platforms: Chromium browsers (Chrome, Arc, Brave).
Download: Claude for Chrome
Bottom line: Best for engineers who already pay for Claude and want the same model working inside DevTools.
2. GitHub Copilot Chat – Best for repo-aware debugging
GitHub Copilot Chat in the browser reads the repo the tab is looking at. On github.com it answers questions about the diff or file open on screen, and on any other tab it falls back to a general assistant.
Where it falls short: Non-GitHub tabs get a much weaker experience. Third-party site debugging is thin.
Pricing:
- Free: 50 chat messages a month with GPT-4.1 mini
- Paid: Copilot Pro at $10/mo, Business at $19/user/mo
- vs Claude for Chrome: better repo context, less browser control
Platforms: Chrome, Edge, Firefox.
Download: GitHub Copilot
Bottom line: The extension to pair with heavy GitHub work.
3. Sider Fusion – Best multi-model sidebar
Sider Fusion puts a sidebar chat next to the tab with a model switcher across GPT-5, Claude Sonnet, Gemini, and Grok. It can read the page, summarize a PDF loaded in the browser, and translate DevTools output on demand.
Where it falls short: DevTools reading is basic. It sees the page, not the network tab. Model rate limits are strict on the free tier.
Pricing:
- Free: limited queries per day
- Paid: Basic $10/mo, Pro $20/mo
- vs Claude for Chrome: broader model choice, shallower browser hooks
Platforms: Chrome, Edge, Firefox, and standalone macOS/Windows apps.
Download: Sider
Bottom line: The right pick if you want to compare model answers on the same page.
4. Monica – Best for sidebar debugging plus writing
Monica blends an AI chat sidebar with writing helpers, PDF chat, and image tools. For debugging it reads the visible page and can be asked to explain a specific error message that is copied in.
Where it falls short: No direct DevTools integration. It reads what the user pastes in, not the browser’s own tools.
Pricing:
- Free: 40 queries per day
- Paid: Pro $8.30/mo billed annually, unlimited queries
- vs Sider: more writing tools, weaker developer features
Platforms: Chrome, Edge, Firefox.
Download: Monica
Bottom line: Useful for full-stack folks who write copy and debug on the same day.
5. Merlin – Best for research plus coding help
Merlin is a general assistant extension that pins to any page and adds shortcuts for “explain this,” “translate,” and “summarize.” Its Ask Anywhere feature is quick for pasting a snippet of code into any input box.
Where it falls short: Not a specialist debugger. It reads the page but does not touch DevTools.
Pricing:
- Free: limited queries per day
- Paid: Pro at $19/mo, Team at $29/user/mo
- vs Claude for Chrome: broader everyday utility, weaker at deep debugging
Platforms: Chrome, Edge.
Download: Merlin
Bottom line: Best if you want one extension to cover a mix of tasks, not a debugger specifically.
6. HARPA AI – Best for web automation
HARPA AI is different. It runs command chains that scrape pages, monitor prices, and post to Zapier. For debugging, it is handy when a bug hides behind a login flow and you want to record the reproduction steps.
Where it falls short: The command language has a learning curve. Overkill for a quick “what does this error mean.”
Pricing:
- Free: capped daily queries and automations
- Paid: Premium at $19/mo, Ultimate at $39/mo
- vs Sider: broader automation, weaker for chat
Platforms: Chrome, Edge.
Download: HARPA AI
Bottom line: Reach for HARPA when the bug reproduction itself is the hard part.
7. Perplexity Companion – Best for cited answers on any tab
Perplexity Companion adds a sidebar that answers with sources. Point it at a Stack Overflow-style question and it returns fresh answers with links, which is how a lot of engineers find “is this behaviour actually a bug in Chrome 130” articles.
Where it falls short: Less capable at direct code editing. It is a research tool that happens to help debugging.
Pricing:
- Free: unlimited standard queries
- Paid: Pro at $20/mo (adds Sonar, GPT-5, and Claude access)
- vs Claude for Chrome: better search, weaker page control
Platforms: Chrome, Edge, Firefox.
Download: Perplexity
Bottom line: The one to have open when the bug looks like a browser regression you need to prove.
How to pick
- If you want the deepest browser hook: Claude for Chrome.
- If you spend most of your day on github.com: GitHub Copilot Chat.
- If you want to A/B multiple models on the same DOM: Sider Fusion.
- If you write copy and debug on the same day: Monica.
- If you need to record a repro flow behind a login: HARPA AI.
- If citations matter: Perplexity Companion.
- If you already pay for a general AI subscription and want quick everyday help: Merlin.
FAQ
Which extension reads Chrome DevTools directly? Claude for Chrome is the one with the strongest DevTools awareness right now. GitHub Copilot Chat and Sider both read visible page content but not the DevTools panels directly.
Can I use a local model with these? Sider Fusion supports local endpoints. Most of the others expect a hosted API. Pair AnythingLLM or Ollama with an OpenAI-compatible proxy for private debugging.
Are these safe with production code? Only if the model provider’s data policy is acceptable. Claude, GitHub, and Anthropic all publish clear enterprise data policies. Read them before pasting private code.
Is any of them free forever? Perplexity Companion has a generous free tier. Everything else caps free usage after a daily limit.
What is the best free AI debugging extension? Perplexity Companion for research-heavy debugging. GitHub Copilot Chat if you have a paid GitHub plan.
