What does HackerNews think of jsmn?

Jsmn is a world fastest JSON parser/tokenizer. This is the official repo replacing the old one at Bitbucket

Language: C

#4 in Parsing
Flattening ASTs and other compiler data structures | Jul 2023
One more JSON implementation using this approach is https://github.com/zserge/jsmn.
Show HN: WinGPT – AI assistant for Windows 3.1 | Jun 2023
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Yep! I'm using JSMN (https://github.com/zserge/jsmn), which is a streaming parser that visits each token sequentially, so there's only one copy of each JSON response in memory. I also avoid allocating new intermediate memory whenever possible; for example, to unescape backslashes in the JSON strings, I use a destructive loop that moves the non-backslash characters forward in memory, and truncates the string by moving the null terminator earlier in the string. Not something I'd imagine doing in most environments today, but as you said, it saves a bit of space at the expense of CPU time :)

  void DestructivelyUnescapeStr(LPSTR lpInput) {
    int offset = 0;
    int i = 0;
    while (lpInput[i] != '\0') {
      if (lpInput[i] == '\\') {
        offset++;
      } else {
        lpInput[i - offset] = lpInput[i];
      }
      i++;
    }
    lpInput[i - offset] = '\0';
  }
CJSON – Ultralightweight JSON parser in ANSI C | Feb 2022
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and https://github.com/zserge/jsmn
CJSON – Ultralightweight JSON parser in ANSI C | Feb 2022
Anyone know how this compares with jsmn? https://github.com/zserge/jsmn
MessagePack: like JSON, but fast and small | Mar 2020
I was looking at MessagePack for communicating to and from my STM32F1-based microcontroller project from the PC controller software I'd be writing. At least the official C library was not optimized for memory usage and code size. I also considered BSON, but it also lacked suitable libraries.

So I ended up using JSON. Yes the message sizes are larger in byte size with JSON but using the jsmn[1] parser I could avoid dynamic memory usage and code size was small. The jsmn parser outputs an array of tokens that point to the buffer holding the message (ie start and end of key name etc), so overhead is quite limited.

For JSON output I modified json-maker[2]. It already allowed for static memory usage and rather small code size, but I changed it to support a write-callback so I could send output directly over the data link, so I didn't have to buffer the whole message. This is nice when sending larger arrays of data for example.

Combined it took about 10kB of program (flash) memory, of which float to string support is about 50%. Memory usage is determined by how larger incoming messages I'd need, for now 1kB is plenty.

A nice advantage of using JSON is that it's very easy to debug over UART.

Though having compact messages would be nice for wireless stuff and similar, so does anyone know of a MessagePack C/C++ library that is microcontroller friendly?

[1]: https://github.com/zserge/jsmn

[2]: https://github.com/rafagafe/json-maker

Writing a Fast JSON Parser | May 2017
For json parsing, I really like JSMN (https://github.com/zserge/jsmn/). It doesn't allocate memory, has a simple and easy to use API, and is pretty fast.
Memory use and speed of JSON parsers | Dec 2015
In the project that I am involved[0], I have been doing stress tests with very large JSON messages. After evaluate a few options I came up that the project 'JSMN' was good enough for my purposes.

    https://github.com/zserge/jsmn
I am not sure if there are Python or another language bindings available but that library is very clean and simple to use. It does not perform memory allocations as you (the caller) have to provide the buffers so it gives you good flexibility.

[0] http://fluentbit.io