BSON

BSON is a computer data interchange format extending JSON. It is a binary form for representing simple or complex data structures including associative arrays, integer indexed arrays, and a suite of fundamental scalar types.
BSON originated in 2009 at MongoDB. Several scalar data types are of specific interest to MongoDB and the format is used both as a data storage and network transfer format for the MongoDB database, but it can be used independently outside of MongoDB.
Implementations are available in a variety of languages such as C, C++, C#, D, Delphi, Erlang, Go, Haskell, Java, JavaScript, Julia, Lua, OCaml, Perl, PHP, Python, Ruby, Rust, Scala, Smalltalk, and Swift.

Data types and syntax

BSON has a published specification. The topmost element in the structure must be of type BSON object and
contains 1 or more elements, where an element consists of a field name, a type, and a value. Field names are strings. Types include:

Unicode string
32-bit integer
64-bit integer
double
decimal128, suitable as a carrier for decimal-place sensitive financial data and arbitrary precision numerics with 34 decimal digits of precision, a max value of approximately 10⁶¹⁴⁵
datetime in UTC
byte array
Boolean
null
BSON object
BSON array
JavaScript code
MD5 binary data
Regular expression

An important differentiator to JSON is that BSON contains types not present in JSON and offers type-strict handling for several numeric types instead of a universal "number" type. For situations where these additional types need to be represented in a textual way, MongoDB's Extended JSON format can be used.

Efficiency

Compared to JSON, BSON is designed to be efficient both in storage space and scan-speed. Large elements in a BSON document are prefixed with a length field to facilitate scanning. In some cases, BSON will use more space than JSON due to the length prefixes and explicit array indices.

Example

A document such as will be stored as:

\x16\x00\x00\x00 // total document size
\x02 // 0x02 = type String
hello\x00 // field name
\x06\x00\x00\x00world\x00 // field value
\x00 // 0x00 = type EOO