All tools

HTTP Range Request Header Builder

Network

Build an HTTP Range request header from byte ranges (explicit, open-ended, or last-N-bytes), and parse a server's Content-Range response to verify what it actually sent back.

A resumable download or a partial-file fetch depends on a correctly formed Range request header, and RFC 7233's byte-range-spec grammar (start-end, start with no end, or a negative suffix length for the last N bytes) is easy to get subtly wrong by hand, especially once you're combining multiple ranges in one request. This assembles that header from a list of ranges, resolves each one's byte length and percentage of the file when you supply a total size, and flags ranges that overlap. It also parses a server's Content-Range response so you can confirm the bytes it actually returned match what you asked for. It builds and parses header values only, it never makes a network request itself.

rangehttpheadersresumable-downloadpartial-contentcontent-range

How to use HTTP Range Request Header Builder

  • 1.Add one or more ranges: an explicit start and end byte, a start with no end (to the end of the file), or a suffix length for the last N bytes.
  • 2.Optionally enter the total file size to resolve open-ended ranges into a byte count and catch overlapping ranges.
  • 3.Copy the generated Range header, or paste a server's Content-Range response into the verifier to check what it actually sent.

Frequently asked questions

Does this download the file or make a request?
No, it only builds and parses header text. Send the actual request with your own HTTP client.
What does a suffix range mean?
A suffix range like -500 asks for the last 500 bytes of the resource, useful for reading a file's trailer without knowing its total size up front.
Why do I need to supply a total size?
Without it, an open-ended range (like 500-) or a suffix range's exact byte count can't be resolved, and overlap between ranges can't be checked.
Does every server support multi-range requests?
No, some servers reject a Range header with more than one range and just return the whole file with a 200 instead of a 206. Check the response status and Content-Range before assuming a multi-range request worked.

Use via API, SDK, or MCP

cURL# Free: 1,000 req/day · Pro: 10,000 req/day
curl -X POST https://api.utilix.tech/v1/tools/http-range-header-builder \
  -H "Authorization: Bearer utx_live_..." \
  -H "Content-Type: application/json" \
  -d '{"ranges":[{"start":0,"end":1023}],"contentRangeHeader":"bytes 200-1000/67589"}'

Get an API key from your dashboard · Full API docs →

Related tools

Cache-Control Header BuilderBuild and explain an HTTP Cache-Control response header from directives like max-age, s-maxage, no-store, and immutableNetworkCORS Header BuilderGenerate CORS headers with nginx, Express, and Apache config snippetsNetworkHTTP ETag GeneratorGenerate a content-hash ETag response header value using MD5, SHA-1, or SHA-256, with strong or weak (W/) validator syntax, ready to drop into a server response.Network