Open CBOR files in your browser
The IETF's binary JSON, inside passkeys, signed certificates and devices too small for text. Open a CBOR file right here as a tree you can fold. Nothing leaves your device.
Or drop it anywhere on this page
What you'll see
Your file opens as a tree, its first levels unfolded on a page as wide as a book.
- Fold and unfold • Files of any size
- Search keys and values • Every match counted
- Tree, Table or Text • Show shape
- Export • Save in another form, or just a part
About CBOR
Carsten Bormann and Paul Hoffman wrote CBOR for the IETF in 2013, and RFC 8949 updated it in 2020. It stores JSON's values in binary, with room for binary data and numbers of any size, for small devices and for protocols: WebAuthn passkeys, COSE signatures and the EU's COVID certificates are CBOR.
Tags say what a value means: tag 0 or 1 makes a date, 2 and 3 big numbers, 37 a UUID and 32 a link. Strings, lists and maps can come in pieces of unknown length, and a file can hold many values one after another.
Filepeek reads the file with its own CBOR reader and lists its values as a tree. Dates, big numbers and UUIDs read as what they are, other tags show their number, binary data opens in its own viewer when it holds a picture or a file it knows, and Save as JSON writes it all out.
Concise Binary Object Representation
.cbor
Format
- MIME type
- application/cbor
- Made by
- Carsten Bormann and Paul Hoffman, in IETF RFC 8949
- Released
- 2013
Inside the file
- Values
- Maps, arrays, strings, numbers and bytes
- Tags
- Dates, big numbers, UUIDs and more
- Lengths
- Known, or until a break
- Standard
- IETF RFC 8949
Opens in every browser
Browsers download CBOR files. Filepeek opens them as a tree in Chrome, Edge, Firefox and Safari.
- YouChromeOpens through Filepeek
- YouEdgeOpens through Filepeek
- YouFirefoxOpens through Filepeek
- YouSafariOpens through Filepeek
Questions
How do I open a CBOR file?
Drop it on this page or choose Peek a CBOR. It opens at once as a tree you can unfold, with nothing to install.
Can I turn CBOR into JSON?
Yes. Choose Export, then Save as JSON or Save as YAML. Binary data is written in base64, and dates and big numbers as they read.
What do the tags mean?
A tag says what the value after it is. Filepeek reads dates, big numbers and UUIDs as what they are, and shows the number of any other tag next to its value.
Is my file uploaded?
No. The file opens inside your browser and never leaves your device.