MongoDB Extended JSON Converter

Extended JSON (EJSON) is MongoDB's JSON dialect. It preserves BSON types that JSON can't represent natively: ObjectId, Date, Decimal128, Int64, Binary, Timestamp, and the rest. Each typed value is wrapped in a $-prefixed object like {"$oid": "…"} or {"$date": "…"}.

Canonical EJSON wraps every value in its type so it round-trips through any BSON driver without ambiguity. Relaxed EJSON uses JSON primitives where the type is unambiguous: bare numbers for int32, ISO date strings instead of {"$date": {"$numberLong": "…"}}. mongosh prints relaxed. mongoexport emits canonical by default.

Use "Plain JSON" when the consumer (a frontend, a test fixture, documentation) doesn't care about BSON types. ObjectIds become hex strings, dates become ISO strings. Use "Relaxed" when you want a human-readable copy that still distinguishes Long and Decimal. Use "Canonical" when you need lossless round-tripping through a BSON driver.

Conversion happens entirely in your browser. Nothing leaves your device. The converter preserves key order within objects, so re-running a conversion is idempotent as long as the target mode stays the same.

The tool doesn't infer BSON types from plain values. There's no reliable way to know if "507f1f77bcf86cd799439011" should be an ObjectId or just a string. For proper round-tripping, start from canonical or relaxed EJSON. If you need to manually wrap a value, paste { "myField": { "$oid": "…" } } and pick your desired output mode.

Yes. The tool handles $oid, $date (string, number, and $numberLong variants), $numberInt, $numberLong, $numberDouble, $numberDecimal, $binary, $timestamp, $regex / $regularExpression, $symbol, $code (with or without scope), $uuid, $minKey, $maxKey, and $undefined. Anything else is treated as a regular JSON object and left unchanged.