HTTP Range Tester: Byte Ranges & Content-Range
Calculate exact HTTP byte ranges, explain modeled 206/416 responses and check Content-Range lengths locally. Inspect strong If-Range matches without requesting a URL.
Enabling local controls…
Results
Review the settings and run. Editing inputs clears old results.
Processing model and limits
Offline GET model: ordinary preconditions already permit 200. Choose whether the server handles or ignores Range; no result proves remote support. Byte offsets refer to the selected encoded representation, not decoded text. Closed/open/suffix ranges, at most 16 members, 30 digits per integer and 4 KiB per field. Empty-resource Range requests, tabs, empty list members, unknown units, date/weak If-Range, multipart body generation and network requests are unsupported. Overlap/order/duplicates are preserved, not merged. Content-Range permits unknown total or */0; compare body bytes only for a satisfied single range. Every byte value is exported as an exact decimal string; output ≤64 KiB. Inputs stay in memory, never uploaded, saved or added to URLs. Review reports before sharing.
Data and model checked: RFC 9110: range requests ↗RFC 9110: If-Range ↗
How to use this tool
Load the example, confirm field units and processing rules, then run locally. Editing any input clears the old result. Copy or download the complete output explicitly.
When not to use it
Do not use the modeled status as proof of server support, authentication or safe resume. Verify the actual encoded representation and response separately; date If-Range and multipart bodies are outside this version.
Read the guide →