RulesEncoding emits definite-length CBOR (shortest integer form, float64 for floats). Decoding covers every major type: byte strings become Base64, tags are unwrapped, half/single/double floats, indefinite-length items, and integers beyond the safe range become strings — each with a counter, nothing dropped silently.

JSON

Load some data to start

CBORHex

Load data and the result will appear here

The binary JSON of WebAuthn & IoT

JSON to CBOR Converter

Two-way encode / decode · Hex & Base64 · every major type · runs locally

🔒Data is processed locally in your browser — never uploaded or stored

No upload, no storage

JSON is processed in memory and never sent to a server.

Share via URL fragment

Share links encode data in the # anchor — never sent to a server.

Remember last edit

Optionally keep your last input locally; clear it with one click.

Why use this JSON to CBOR converter

Read binary payloads

WebAuthn credentials, COSE keys and IoT telemetry ship as CBOR — paste the Hex or Base64 and get readable JSON instantly.

Two-way conversion

Encode JSON to CBOR to check sizes and verify encodings; decode CBOR back to JSON to inspect fields — one page, both directions.

Every major type

Byte strings, tags, half/single/double floats, indefinite-length items and big integers are all handled, each conversion counted and reported.

Precise error positions

Truncated data, trailing bytes and illegal encodings all report an exact byte offset — not a vague parse error.

Local & private

Credentials and device data are sensitive — everything is encoded and decoded on your machine, nothing uploaded.