01
Choose the byte format explicitly
Hex is the default and accepts spaces, colons and 0x prefixes. Switch to Base64 if that is what your capture contains; short strings can be valid in more than one encoding.
Protocol bytes, explained
Protobuf decoder
Paste a raw message, then add a self-contained .proto only when you need declared names and types.
Protobuf decoder
Optional .proto schema
Bytes and schema are processed in this browser, without upload.
Options
Enter a wire message or varint.
A Protobuf decoder is useful when a log contains bytes but no readable field names. The wire stream still tells you where every field starts, how it is encoded, and exactly which bytes belong to it.
A protobuf wire decoder cannot infer whether a length-delimited value was a string, nested message or packed data. Compare tentative readings against the raw hex, or supply a schema before treating any value as typed.
Why use this Protobuf decoder?
Keep the evidence beside each interpretation.
Trace a field back to the payload
This Protobuf decoder shows field number, wire type, half-open byte offsets and the original hex together. A malformed length points to its first impossible byte instead of leaving you with an unexplained empty result.
Add meaning without losing the wire view
Paste a single .proto and choose a message to get typed JSON. The named result sits beside the same raw fields, so you can check where a declared string or integer came from.
Three checks before trusting a decoded value
02
Treat raw readings as candidates
Wire type 0 carries unsigned bits that might represent signed integers, ZigZag values, booleans or enums. Wire type 2 can hold text, bytes, packed numbers or another message. Only a schema settles the intended type.
03
Check freshness and offsets
Automatic decoding waits 350 ms after an edit. Turn it off for Ctrl/Cmd + Enter. Any input or option change disables export until the new run finishes; offsets start at zero and the end excludes the next byte.
What the bytes reveal
Four common wire types
The Protobuf decoder reads varint, fixed64, length-delimited and fixed32 records. It rejects truncated keys, impossible lengths and deprecated group tags instead of silently skipping unknown spans.
A precise varint workbench
Use the protobuf varint decoder to read up to ten bytes as exact uint64 and optional sint64 ZigZag. Reverse direction to encode a decimal value; BigInt avoids JavaScript Number precision loss.
Schema-backed JSON
A self-contained .proto can name fields and decode repeated or nested values with protobuf.js. Select the root message when the file defines several; the raw wire tree remains visible if schema interpretation fails.
Hex that matches the input
The protobuf hex decoder exports normalized uppercase hex of the original payload. It never re-encodes a guessed message, so byte comparisons against the capture remain meaningful.
Where the wire format stops
- Field names require a schema
- A Protobuf decoder without schema can recover field numbers and wire types, not original names, enum labels or oneof intent. Guessed names would turn an ambiguity into a false fact.
- Length-delimited remains ambiguous
- Readable UTF-8 and a valid nested parse are both candidates, not proofs. Compare raw bytes with the source .proto before using either in application logic.
- One local schema file
- Imports, remote URLs and dependency fetching are outside this tool. Paste a self-contained proto2 or proto3 definition; syntax failures are reported with their line where available.
- A payload, not a transport frame
- The input is one raw wire message. The tool does not strip gRPC framing, decompress data or encode a complete JSON object back into Protobuf. Groups 3 and 4 are rejected explicitly.
Protobuf decoder questions
Can I decode protobuf without a .proto file?
Yes, for wire structure. You can see field numbers, wire types, offsets and raw values. Declared names and exact types require a matching .proto.
How do I decode a protobuf hex dump?
Choose Hex, paste pairs of digits, and inspect the numbered fields. An odd digit or truncated field produces an error rather than a partial success.
Why do I see multiple interpretations for one field?
The wire format stores only a small type code. The same bytes may legitimately be an unsigned integer, ZigZag integer, string, bytes or embedded message.
How do I use protoc to decode protobuf files?
protoc --decode_raw can inspect unknown wire data; protoc --decode needs a compiled message type. This browser tool offers a similar raw view and optional local schema.
How do I extract a varint from a serialized protobuf file?
A varint starts after a wire-0 field tag and ends at the first byte whose top bit is clear. The standalone Varint mode accepts that byte sequence directly.
Found a definition that should be supported?
Inspect the next Protobuf payload
Return to the Protobuf decoder when a captured message needs a byte-for-byte explanation. Keep the original hex and the declared schema together for the final review.