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Convert JSON to CBOR (RFC 8949) hex and back. CBOR is the compact binary format used in COSE, WebAuthn and IoT. Everything runs in your browser.
Convert JSON to CBOR (RFC 8949) hex and back. CBOR is the compact binary format used in COSE, WebAuthn and IoT. Runs entirely in your browser.
CBOR (Concise Binary Object Representation, RFC 8949) is a compact binary data format with the same data model as JSON but a much smaller, faster encoding. It is the backbone of COSE signatures, WebAuthn/FIDO2 attestation, and many constrained IoT protocols. This tool encodes JSON into CBOR shown as hex, and decodes CBOR hex back into readable JSON.
Input:
{ "a": 1, "b": [2, 3] }Output:
a26161016162820203
Where is CBOR used?
COSE (signed/encrypted CBOR), WebAuthn and FIDO2 credentials, CWT tokens, and lightweight IoT messaging all use it.
What values are supported?
The JSON-compatible set: integers, floats, strings, arrays, maps with string keys, booleans and null. Tags and indefinite-length items are not produced.
Why is the output hex?
CBOR is binary, so it is shown as hex for easy copying and inspection. Paste hex back to decode.
Is anything uploaded?
No. Encoding and decoding run entirely in your browser.