How to Do Axios Interceptors on Claude Code

Claude Code can scaffold axios interceptors for you in seconds: describe what you need (auth token injection, retry logic, error normalization), and it generates a production-ready interceptor file. This works best for frontend and Node.js developers who want to centralize HTTP logic without writing boilerplate by hand.

• Claude Code handles request and response interceptors in a single prompt
• Covers common patterns: Bearer token injection, 401 refresh flows, global error toasts
• Long sessions consume tokens fast; use usage tracking to avoid a mid-task lockout

What are axios interceptors and why use Claude Code to write them?

Axios interceptors are middleware hooks that run before a request is sent or after a response is received. They are the standard pattern for attaching authentication headers, logging, retry logic, and centralized error handling to every HTTP call in a JavaScript or TypeScript project.

Writing interceptors by hand is repetitive. The pattern is well-defined but the wiring, edge cases (token expiry, refresh race conditions, network timeouts), and TypeScript generics add friction. Claude Code eliminates that friction: you describe the behavior you want and it produces a complete, typed implementation you can drop straight into your codebase.

How to prompt Claude Code for axios interceptors

Open your terminal in your project root and launch Claude Code. The key is to be specific about what the interceptor should do. Vague prompts produce generic output; concrete prompts produce code you can actually ship.

Basic request interceptor: attaching a Bearer token

Start with the simplest case. Try a prompt like:

"Create an axios instance in src/lib/api.ts. Add a request interceptor that reads a JWT from localStorage under the key access_token and attaches it as a Bearer Authorization header on every request."

Claude Code will generate the instance setup, the interceptor hook, and the TypeScript types. It will also remind you to handle the case where the token is null.

Response interceptor: global error handling

For error normalization, a prompt like this works well:

"Add a response interceptor to the same axios instance. On any 4xx or 5xx response, extract the error message from error.response.data.message and throw a normalized AppError class with a status field. On network errors, throw with status 503."

This gives you a single place to handle errors across the whole app, instead of scattered catch blocks.

Refresh token flow with a retry queue

This is where interceptors get tricky to write by hand. The classic 401-refresh pattern requires queuing concurrent requests while a token refresh is in flight. Prompt Claude Code like this:

"Extend the response interceptor to handle 401 errors. When a 401 is received: call a refreshToken() function, queue any concurrent failed requests, retry them once the refresh resolves, and redirect to /login if the refresh itself returns 401. Use a promise queue pattern to avoid multiple simultaneous refresh calls."

Claude Code knows this pattern and will produce the isRefreshing flag, the failedQueue array, and the retry logic in a single pass.

Practical tips for working on interceptors in Claude Code

Give Claude Code your existing axios instance

If you already have an axios.create() instance, open that file in your editor and tell Claude Code to modify it rather than create a new one. This prevents duplicate instances and import conflicts. You can use Claude Code slash commands like /add to include specific files in context.

Ask for tests alongside the implementation

Interceptor logic is notoriously easy to break. After generating the interceptor, follow up with:

"Write Jest unit tests for this interceptor. Test: token attached correctly, 401 triggers refresh, refresh failure redirects to /login, non-401 errors are passed through as AppError."

Combine with other middleware patterns

Interceptors pair naturally with other patterns Claude Code handles well. You can chain prompts to add rate limiting logic inside a request interceptor, or wire up Express middleware on the server side that mirrors the client interceptor behavior.

Keep sessions focused to conserve tokens

Axios interceptor work tends to snowball: you start with token injection, then add refresh logic, then add logging, then add retry with exponential backoff. Each iteration is a token cost. Long, broad sessions burn through your Claude usage limit faster than short, focused ones. If you hit your limit mid-refactor you lose the thread and have to reconstruct context from scratch.

Knowing where you stand before that happens is the difference between shipping and waiting five hours for a reset. The /usage command in Claude Code gives you a snapshot, and Usagebar puts your live usage in the macOS menu bar with alerts at 50%, 75%, and 90% so you never hit the wall mid-session.

Common axios interceptor patterns and how to prompt for them

Pattern	What to include in your prompt	Watch out for
Bearer token injection	Token storage key, header name, null case behavior	SSR environments where localStorage is unavailable
401 refresh + retry	Refresh endpoint, queue pattern, redirect on failure	Infinite refresh loops if refresh itself returns 401
Request logging	What to log (method, URL, payload), log level, env gating	Logging sensitive auth headers in production
Global error normalization	Error shape from your API, custom error class structure	Swallowing errors that calling code needs to handle
Retry on network failure	Max retries, backoff strategy, which status codes to retry	Retrying non-idempotent POST requests unintentionally
Request cancellation	CancelToken or AbortController pattern, where to call cancel	Memory leaks from uncancelled requests on unmount

Checking your Claude Code usage during a long interceptor session

Interceptor work often starts as a quick task and expands. Token usage climbs fast when you are iterating on complex async patterns or asking Claude Code to generate tests. There are three ways to track where you stand:

• Run /usage in the Claude Code terminal to see a current snapshot
• Visit claude.ai/settings/usage for a full breakdown by session
• Use Usagebar for passive, always-on monitoring in your macOS menu bar, with smart alerts before you hit the limit

The five-hour reset window is a real constraint. If you are deep in a refresh token implementation and your session cuts out, you lose both the working context and momentum on the PR. Usagebar's 90% alert gives you time to wrap up, commit a working state, and come back clean after the reset. Check the Claude Code usage reset schedule so you can plan sessions around the window.

Monitor your usage while you build: Usagebar

Usagebar is a lightweight macOS menu bar app built specifically for Claude Code users. It shows your live usage percentage at a glance, fires alerts at 50%, 75%, and 90%, and stores credentials securely in the macOS Keychain. There is no subscription required to start: it is pay-what-you-want, with a free tier for students.

For developers who rely on Claude Code for tasks like axios interceptor work, knowing your usage window prevents the worst outcome: being locked out of a session mid-PR when you are in the middle of a tricky async pattern. Get Usagebar for instant download and start your next Claude Code session with full visibility.

Key takeaways

1. Be specific in your prompts: name the token key, error shape, and queue pattern you want
2. Give Claude Code your existing axios instance to avoid duplicate setups
3. Request tests in the same session while context is fresh
4. Chain to related prompts (rate limiting, Express middleware) for full-stack consistency
5. Track token usage with /usage or Usagebar to avoid a mid-session cutoff
6. Know your reset window so you can plan complex sessions around it