W3C Trace Context Parser

How to use

1. 1Pick a tab: Parse traceparent for a single header (or a list), Parse tracestate for the vendor entries, or Build headers to compose a new pair from a form.
2. 2On Parse traceparent, paste the header value (the leading "traceparent:" prefix is optional) and read the version, trace-id, span-id, and decoded trace-flags. Sampled and random-trace-id bits are shown as badges; reserved bits are flagged with warnings.
3. 3On Parse tracestate, paste the comma-separated key=value list. Each entry is checked against the W3C grammar (lowercase keys, tenant@vendor multi-tenant form, value charset) with per-entry byte counts and total header size.
4. 4Use the sample buttons to load valid and invalid examples (uppercase hex, all-zero IDs, too many entries) so you can see exactly which errors each one produces.
5. 5On Build headers, click Generate random IDs to mint a 16-byte trace-id and 8-byte span-id, toggle the sampled and random-trace-id flags, paste any tracestate vendor entries, and copy curl, fetch, Node, OpenTelemetry JS, or Go snippets from the result.

About this tool

W3C Trace Context Parser decodes the traceparent and tracestate HTTP headers that propagate distributed traces across services. Paste a traceparent value and the tool splits it into version, trace-id, span-id, and trace-flags, then validates each field against the W3C Trace Context Level 2 grammar: 32 lowercase hex chars for trace-id, 16 lowercase hex chars for span-id, and an 8-bit flags byte with bit 0 (sampled) and bit 1 (random-trace-id) decoded into named badges. Common mistakes are caught and explained: uppercase hex, the reserved version ff, the all-zero trace-id and span-id, the wrong number of hyphen-separated fields, and the exact 55 character length rule for version 00. Paste a tracestate value and each comma-separated key=value entry is broken out with the simple-key versus tenant@vendor grammar, the value charset (printable ASCII without commas or equals), the per-entry 256 byte limit, the 32 entry maximum, and the 512 byte soft cap that proxies use to decide whether to forward the header. Duplicate keys, stray commas, oversized values, and uppercase keys all surface as targeted errors so you know exactly which entry to fix. The Build tab composes a traceparent from a small form (with a Generate random IDs button that mints a fresh trace-id using crypto.getRandomValues), lets you toggle the sampled and random-trace-id bits, and accepts an optional tracestate payload. Copy-ready snippets for curl, JavaScript fetch, Node.js https, the OpenTelemetry JS propagation.extract API, and Go OTel HeaderCarrier injection are produced live so you can drop a working request into the codebase you are debugging. Useful for developers integrating OpenTelemetry into a new service, SREs reading log lines that include only the raw traceparent, vendors implementing W3C propagation, and anyone debugging why a downstream service is starting a new trace instead of joining the parent. Everything runs locally; the headers you paste, the random IDs you mint, and the snippets you copy never leave your browser.

Free to use. Works in your browser. No signup, no login.