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CBOR converter

A .cbor file holds Concise Binary Object Representation data: a binary format built on the JSON data model but standardized by the IETF, with a tag mechanism that lets it carry dates, big integers, decimals and arbitrary application types without inventing a convention for each one.

Private for supported formats — processed in your browser

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Runs on your device

Drop CBOR files here

Batch files can each use a different output. Nothing uploads for local conversions.

Working inputs include camera RAW, browser-local audio/video, PDF, CBZ/CBR comics, office documents, ebooks, markup, 3D models, structured text, images, and archives.

Where CBOR comes from

Carsten Bormann and Paul Hoffman specified CBOR in RFC 7049 in 2013, aiming for a format that could be implemented in very little code on constrained devices while remaining extensible. RFC 8949 replaced it in 2020 as an Internet Standard. Its reach comes from where it was adopted rather than from general popularity: WebAuthn and FIDO2 credentials, COSE signing, the CoAP-based IoT stack, and the C2PA content-provenance manifests now attached to images all use CBOR.

How CBOR works

  • Every item begins with a major type in the top three bits and a length or value in the remaining five, which makes decoders small enough for microcontrollers.
  • Tags (major type 6) attach semantics to a following item — tag 0 is an RFC 3339 date string, tag 2 a big integer, tag 4 a decimal fraction.
  • Indefinite-length arrays, maps, strings and byte strings can be emitted before the total size is known, which suits streaming producers.
  • Byte strings are a distinct type from text strings, so binary data needs no base64 wrapper.
  • Canonical and deterministic encoding rules are specified, which is why signature formats can rely on CBOR at all.

When to use CBOR

  • WebAuthn and FIDO2 attestation and assertion payloads
  • Constrained IoT messaging over CoAP where every byte matters
  • Signed and encrypted structures using COSE
  • Reading a captured CBOR payload as JSON or a table during debugging

Strengths and limitations

Strengths

  • An actual IETF standard with a stable, versioned specification
  • Tags express types JSON cannot, without breaking decoders that ignore them
  • Deterministic encoding rules make it usable inside signatures

Limitations

  • Tag semantics are only as portable as the two ends' agreement on them
  • Indefinite-length items complicate otherwise simple decoders
  • Binary, so inspection needs tooling

Compatibility

Libraries are widely available for C, Rust, Go, Python, Java, JavaScript and .NET, and browsers speak CBOR indirectly through the WebAuthn API. Novus Convert normalizes .cbor locally into a JSON-compatible model and writes JSON, CSV, XLSX, YAML or YML. Tagged values that JSON cannot represent are converted to a documented textual form rather than being silently discarded.

Semantic tags are read and reported; JSON and YAML targets receive their normalized textual form, since neither has a tag mechanism.

Convert CBOR to another format

Convert other formats to CBOR