Binary JSON — MongoDB's storage format. Adds types that JSON lacks (ObjectId, Date, Binary, Decimal128) and encodes them in a compact binary layout. Every MongoDB document is stored as BSON.

When do I see BSON hex?

MongoDB wire protocol dumps, sharding replication logs, and driver debugging output. Rare in day-to-day work; essential when diagnosing low-level DB issues.

Does it preserve BSON-specific types in JSON?

Approximations: ObjectId as 24-char string, Date as ISO 8601 string, Binary as base64. The conversion is lossy for types that have no JSON equivalent — round-tripping back may differ.

Can I convert JSON to BSON?

Yes, bidirectional. Input JSON is parsed and serialized as BSON hex. Types with MongoDB semantics (ObjectId-style strings) are upgraded automatically.

BSON ↔ JSON | DevTools Surf

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Example: BSON ↔ JSON

A worked example, rendered from real sample data. Sign in to run the tool on your own input.

Input

{"_id":{"$oid":"65f3a1b2c4d5e6f7a8b9c0d1"},"name":"Alice","createdAt":{"$date":"2024-03-15T10:30:00Z"},"visits":{"$numberLong":"1024"}}

Output

{
  "_id": "65f3a1b2c4d5e6f7a8b9c0d1",
  "name": "Alice",
  "createdAt": "2024-03-15T10:30:00Z",
  "visits": 1024
}

About BSON ↔ JSON

Convert between BSON hex and JSON. Part of the DevTools Surf developer suite. Browse more tools in the Converters collection.

Use Cases

Debug MongoDB wire protocol messages during driver development
Inspect raw BSON data from database exports
Convert BSON dumps to human-readable JSON for analysis
Validate BSON encoding in custom MongoDB client implementations

Tips

Paste BSON hex strings to see the decoded JSON structure
Convert JSON to BSON hex for MongoDB wire protocol debugging
Inspect ObjectId timestamps embedded in BSON documents

Fun Facts

BSON (Binary JSON) was created by MongoDB Inc. in 2009 and supports data types JSON lacks, including Date, Binary, and ObjectId.
A MongoDB ObjectId is exactly 12 bytes: 4 bytes for timestamp, 5 bytes for random value, and 3 bytes for an incrementing counter.
BSON documents have a maximum size of 16 megabytes in MongoDB, a limit chosen to prevent any single document from consuming excessive RAM.

FAQ

What is BSON?: Binary JSON — MongoDB's storage format. Adds types that JSON lacks (ObjectId, Date, Binary, Decimal128) and encodes them in a compact binary layout. Every MongoDB document is stored as BSON.
When do I see BSON hex?: MongoDB wire protocol dumps, sharding replication logs, and driver debugging output. Rare in day-to-day work; essential when diagnosing low-level DB issues.
Does it preserve BSON-specific types in JSON?: Approximations: ObjectId as 24-char string, Date as ISO 8601 string, Binary as base64. The conversion is lossy for types that have no JSON equivalent — round-tripping back may differ.
Can I convert JSON to BSON?: Yes, bidirectional. Input JSON is parsed and serialized as BSON hex. Types with MongoDB semantics (ObjectId-style strings) are upgraded automatically.

Related Converters Tools

JSON to XML JSON to CSV JSON to YAML JSON to TSV JSON to String XML to JSON XML to CSV XML to String