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Mock HTTP Header Generator

Used by developers, writers, and creators worldwide.

A mock HTTP header generator saves real time when you need realistic request headers for API testing, middleware validation, or traffic simulation. Handwriting header sets is slow, and minimal test headers miss edge cases that only surface with real client signatures — a missing Accept-Language can break localization logic, a wrong Content-Type silently fails parsing. A single missing Sec-Fetch-Mode can expose a gap in your CORS policy. This tool generates complete, self-consistent header sets for browser, mobile, or API client profiles. User-Agent, Accept, Authorization, and related fields align with the chosen client type. Pick how many sets you need and which request type to simulate, then paste directly into Postman, curl, or your test fixtures.

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How to use

  1. Choose your options above
  2. Click Generate
  3. Copy your result

Detailed instructions

  1. Set the Count field to the number of distinct header sets you need for your test scenario.
  2. Choose a Request Type from the dropdown — browser, mobile, or API client — to match the traffic you want to simulate.
  3. Click Generate to produce the header sets, then review each set for the fields relevant to your use case.
  4. Copy the entire set or individual header lines and paste them into Postman, a curl command, or your test fixture file.

Use Cases

  • •Seeding a Postman collection with browser, mobile, and API client header sets to simulate diverse traffic against a staging endpoint
  • •Testing Express.js middleware that parses User-Agent strings for device detection before it ships to production
  • •Reproducing a client-specific bug where a malformed Accept-Encoding header caused a Flask response to decompress incorrectly
  • •Loading realistic header fixtures into k6 or Locust scripts so caching and routing logic sees varied client signatures under load
  • •Validating CORS configuration by firing browser-profile requests that include Origin and Referer fields at your API endpoint

Tips

  • →Generate browser and API-client sets separately and compare responses — differences often reveal auth or content negotiation bugs.
  • →When testing User-Agent parsing, generate at least five sets and include Random type to catch edge cases your parser may not handle.
  • →For CI test fixtures, generate a batch of eight sets once and commit them to your repo rather than generating fresh ones each run, ensuring reproducible tests.
  • →Combine a generated Authorization header with your actual test credentials to validate that your auth middleware accepts the correct token format.
  • →If your server reads Accept-Language for localization, check the generated value and confirm your logic handles the q-factor weighting syntax it includes.
  • →Use the mobile request type when testing responsive APIs or endpoints that return different payloads based on detected device type.

FAQ

what HTTP headers does this generator actually include

Each set typically includes User-Agent, Accept, Accept-Language, Accept-Encoding, Content-Type, and Authorization. Browser profiles add fields like Sec-Fetch-Mode and DNT, while API client profiles emphasize Content-Type and Authorization headers common to REST and GraphQL consumers. The exact fields shift based on the Request Type you select, so values stay internally consistent rather than mixing headers that would never appear together in a real request.

are the authorization tokens in these headers usable against real APIs

No — generated Authorization values match real formats (Bearer tokens, Basic auth credentials, API keys) but are not tied to any live account or service. They are useful for verifying that your parser accepts the correct format and that middleware routes or rejects requests as expected. For tests that hit a real authenticated endpoint, replace the generated token with a valid credential from your test environment.

what is the difference between the browser mobile and API client request types

Request Type controls which client profile the headers simulate. Browser sets include Sec-Fetch-Mode, DNT, Origin, and Referer — fields real browsers send automatically — while mobile sets use mobile OS User-Agents and may include platform headers like X-Requested-With. API client sets focus on Content-Type and Authorization typical of REST or GraphQL consumers, omitting browser-only fields that would look out of place from a backend service or SDK.