JSON to CBOR Converter
Processing entirely on your device — large files may take a moment.
JSON Data and Concise Binary Object Representation exist for different jobs: JSON (JavaScript Object Notation) is the data exchange format of the web — human-readable text that APIs, apps and configuration files all speak natively. Decode CBOR to JSON to inspect what a device or token actually sent.
Because the whole conversion happens on your device, it is instant, unlimited and genuinely private — no accounts, no watermarks, no files on anyone's server. Multiple files are converted in one go.
How JSON compares to CBOR
| JSON | CBOR | |
|---|---|---|
| Structure | Trees of objects and arrays | Binary tagged values |
| Types / schema | Six native types | Numbers, strings, arrays, maps |
| Compatibility | Universal, machine-first | WebAuthn, COSE, IoT |
| Best for | APIs, app data, config-as-code | Compact machine-to-machine data |
How to convert JSON to CBOR
- 1
Select your files
Drag & drop your JSON files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to CBOR". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted CBOR file individually, or grab everything at once as a ZIP archive.
About the JSON format
JSON (RFC 8259, popularized by Douglas Crockford) is the lingua franca of program data. It has exactly six types — string, number, boolean, null, array, object — nested into trees, and every language on earth parses it natively. REST APIs, NoSQL documents, browser configuration, package manifests: if software talks to software, JSON is usually the sentence.
The spec is deliberately strict: double quotes only, no trailing commas, no comments. That rigidity makes parsers trivial and interop reliable, but it also makes JSON awkward for hand-edited config (people bolt comments on and break parsers) and its 1:1 text mapping keeps large files heavier than binary alternatives.
+ Strengths
- ✓Native parsing in every language
- ✓Six clear types, nesting as deep as needed
- ✓The default of APIs and modern tooling
! Limitations
- −No comments — poor fit for hand-edited config
- −Strict syntax: trailing commas and single quotes break it
- −Verbose; large files parse slowly
About the CBOR format
CBOR (RFC 8949) is what happens when JSON decides to stop wasting bytes: the same objects, arrays, strings and numbers, but length-prefixed binary instead of text. It is the credential format inside WebAuthn passkeys, the payload format of COSE signing and a favourite of embedded devices that cannot afford verbose JSON.
Decoding CBOR to JSON is the everyday debugging move: dump what a token, sensor or authenticator actually sent, then read it like ordinary JSON. The mapping is lossless for the data model both formats share.
+ Strengths
- ✓IETF standard with a strict data model
- ✓Much smaller than equivalent JSON
- ✓Round-trips to JSON without data loss
! Limitations
- −Not human-readable without a decoder
- −Fewer tools speak it than JSON
Why convert JSON to CBOR?
There is a concrete reason this conversion exists: No comments — poor fit for hand-edited config CBOR sidesteps that — IETF standard with a strict data model If that is your situation, the tool above settles it in seconds, entirely on your device.
Frequently asked questions
Is this JSON to CBOR converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
Is there a file size limit for JSON to CBOR?
The only limit is your device's memory, since nothing is uploaded. Files up to a few hundred megabytes work fine on a modern desktop browser; very large files simply take a little longer.
Are formulas, styles or multiple sheets converted?
No — this conversion extracts the data itself into CBOR. Formulas are exported as their current values, styling is not carried over, and multi-sheet workbooks convert sheet by sheet. For full fidelity between spreadsheet formats, exchange within the same tool family.
Is my data safe here?
Yes. The conversion is plain JavaScript running in your tab: the data is parsed and re-serialized in memory, never sent anywhere, and disappears when you close the page.