Comparison of JSON Like Serializations – JSON vs UBJSON vs MessagePack vs CBOR

Recently I’ve been working on some extensions to ASEXOR, adding there direct support for messaging via WebSocket and I use JSON for small messages that travels between client (browser or standalone)  and backend.  Messages looks like these:

I wondered, if choosing different serialization format(s) (similar to JSON, but binary) could bring more efficiency into the application –  considering  both message size and encoding/decoding processing time.  I run small tests  in python (see tests here on gist) with few established serializers, which can be used as quick replacement for JSON and below are results:

Format Total messages size (bytes) Processing time – 10000 x encoding/decoding all messages
JSON (standard library) 798 833 ms
JSON (ujson) 798 193 ms
MessagePack (official lib) 591 289 ms
MessagePack (umsgpack) 585 3.15 s
CBOR 585 163 ms
UBJSON 668 2.28 s

As messaging can use clients in web browser we can also look at performace  of some serializers in Javascript on this page.  As JSON serialization in part of browsers Web API, unsurprisingly it’s fastest there.

In Python pure Python libraries (UBJSON, MessagePack with umsgpack package) are slowest ( but their performance might get better in PyPy).  Standard library implementation of JSON serializer can be easily replaced by better performing ujson package.


JSON is today really ubiquitous, thanks to it’s ease of use and readability.  It’s probably good choice for many usage scenarios and luckily JSON serializers show good performance.   If size of messages is of some concern, CBOR looks like great, almost  instant replacement for JSON, with similar performance in Python ( slower performance in browser is not big issues as browser will process typically only few messages)  and 27% smaller messages size.

If size of messages is big concern carefully designed binary protocol ( with Protocol Buffers for instance) can provide much smaller messages ( but with additional costs in development).

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