CBOR Decoder Online | CBOR to JSON Viewer

CBOR decoder online: turn CBOR hex or Base64 into diagnostic notation, JSON or annotated hex. Decodes WebAuthn, COSE and CWT payloads in your browser. Free. Designed specifically for developers and professionals, this free online decoder runs entirely in your browser to process tasks quickly and securely. Enjoy unlimited usage with no data tracking and no registration required.

Also known as: cbor decoder · cbor decoder online · cbor to json · cbor diagnostic notation · decode cbor hex · cbor parser online · cbor base64 decoder · cose cbor decoder · webauthn cbor decoder

encoding and decoding tools

jwt and auth tools

decoders

CBOR Input

Input bytes as

Decoded CBOR

Decoded CBOR will appear here as a tree of maps, arrays, tags and values you can expand, filter and copy.

About CBOR Decoder

This CBOR decoder turns Concise Binary Object Representation bytes into readable diagnostic notation, JSON or an annotated hex dump. Developers use it to debug WebAuthn attestation objects, COSE keys and signatures, CBOR Web Tokens, and IoT payloads sent over CoAP. It implements RFC 8949 by hand, so every major type, tag and float width is decoded exactly.

Key Features

Decodes all eight major types, including 64-bit integers, bignums, half, single and double floats, and simple values
Handles indefinite-length arrays, maps and chunked byte or text strings, and shows them with the (_ ) and [_ ] markers
Three output views: RFC 8949 diagnostic notation, JSON per section 6.1, and a byte-by-byte annotated hex dump
Names common tags such as 0 (date/time), 18 (COSE_Sign1), 24 (embedded CBOR), 37 (UUID) and 61 (CWT)
Decodes CBOR sequences (RFC 8742) and reports truncated input, reserved bytes and invalid UTF-8 with the exact byte offset
Warns about duplicate map keys and integers too large for JavaScript's JSON.parse

Use Cases

Inspect the attestationObject a passkey returns during WebAuthn registration in Chrome or Safari
Read the integer-keyed map inside a COSE_Key to check the curve and key type an authenticator sent
Debug a CBOR Web Token issued by an identity provider before verifying its signature
Decode telemetry from an ESP32 or Raspberry Pi sensor that posts CBOR over CoAP or MQTT
Compare the bytes your Go, Rust or Python encoder writes against the diagnostic notation in a spec
Check a Matter or Thread smart-home commissioning payload captured during development

Supported Formats

Hex with spaces, colons, 0x prefixes or h'...' wrapping

Base64 and base64url, with or without padding

Decimal or hex byte arrays

Annotated hex with # comments

.cbor, .cwt, .cose and .bin files

Related Keywords

cbor decoder

cbor decoder online

cbor to json

cbor diagnostic notation

decode cbor hex

cbor parser online

cbor base64 decoder

cose cbor decoder

webauthn cbor decoder

What is CBOR used for?

CBOR (RFC 8949) is a binary data format with the same data model as JSON plus byte strings, tags and 64-bit integers. It is used where payloads must be small and parsers simple: WebAuthn and passkeys encode attestation objects and public keys in it, COSE and CBOR Web Tokens build signatures and tokens on it, and constrained IoT devices send it over CoAP. Diagnostic notation is the human-readable text form that specs use in their examples.

Privacy & Security

All processing happens locally in your browser. Your data never leaves your computer, ensuring complete privacy and security.

Liked this tool?

DevToolLab is free to use. If this decoder saved you some time today, please consider supporting our work.

Buy us a coffee ☕

Frequently asked questions

What is CBOR Decoder Online used for?

CBOR decoder online: turn CBOR hex or Base64 into diagnostic notation, JSON or annotated hex. Decodes WebAuthn, COSE and CWT payloads in your browser. Free.

Is CBOR Decoder Online free to use?

Yes. CBOR Decoder Online is completely free with no usage limits, and there is no paid tier required to use it.

Do I need an account to use CBOR Decoder Online?

No. CBOR Decoder Online works immediately in your browser with no signup, login, or email address required.

Related Tools

JWT Decoder | Decode JSON Web Tokens Online Free

Decode JSON Web Tokens (JWT) to view header, payload, and signature. Check token expiration and validate JWT format. Free, secure, and privacy-first.

json tools

encoding and decoding tools

Base64 to Image Decoder Online | Decode Base64 Image

Convert Base64 strings to images instantly. Visualize Base64 image data and download as image files. Support for PNG, JPG, GIF, WebP, and SVG.

text tools

image tools

Snowflake ID Decoder | Discord, Twitter/X & Instagram ID to Timestamp

Decode Discord, Twitter/X, and Instagram snowflake IDs into timestamps and worker IDs instantly in your browser. Free, no signup, bulk decoding supported.

encoding and decoding tools

date and time tools

More Tools You Might Like

Pastebin Online | Share Code & Text Snippets Free

Popular

Share code snippets, logs, and text with a shareable link. Syntax highlighting for 30+ languages, expiration controls, and password protection for Pro users.

text tools

password and key generators

math calculators

utilities

Use Tool

URL Tracker & Link Shortener | Track Clicks

Popular

Create short, trackable URLs with detailed click analytics. Track visitor location, devices, referrers, and more. Password protection & QR codes included.

text tools

password and key generators

url and link tools

networking

Use Tool

Webhook Receiver & Inspector | Test HTTP Webhooks

Popular

Generate a unique URL to easily test, receive and inspect HTTP webhooks in real-time. View request headers, query parameters, JSON payloads, and more.