Parsing gigabytes of JSON per second : used by Facebook/Meta Velox, the Node.js runtime, WatermelonDB, Apache Doris, Milvus, StarRocks (by simdjson)

Simdjson Alternatives

Similar projects and alternatives to simdjson

NOTE: The number of mentions on this list indicates mentions on common posts plus user suggested alternatives. Hence, a higher number means a better simdjson alternative or higher similarity.

simdjson reviews and mentions

Posts with mentions or reviews of simdjson. We have used some of these posts to build our list of alternatives and similar projects. The last one was on 2024-01-01.
  • Use any web browser as GUI, with Zig in the back end and HTML5 in the front end
    17 projects | | 1 Jan 2024
    String parsing is negligible compared to the speed of the DOM which is glacially slow:

    Come on, people, make an effort to learn how insanely fast computers are, and how insanely inefficient our software is.

    String parsing can be done at gigabytes per second: If you think that is the slowest operation in the browser, please find some resources that talk about what is actually happening in the browser?

  • Cray-1 performance vs. modern CPUs
    4 projects | | 25 Dec 2023
    Thanks for all the detailed information! That answers a bunch of my questions and the implementation of strlen is nice.

    The instruction I was thinking of is pshufb. An example ‘weird’ use can be found for detecting white space in simdjson:

    This works as follows:

    1. Observe that each ascii whitespace character ends with a different nibble.

    2. Make some vector of 16 bytes which has the white space character whose final nibble is the index of the byte, or some other character with a different final nibble from the byte (eg first element is space =0x20, next could be eg 0xff but not 0xf1 as that ends in the same nibble as index)

    3. For each block where you want to find white space, compute pcmpeqb(pshufb(whitespace, input), input). The rules of pshufb mean (a) non-ascii (ie bit 7 set) characters go to 0 so will compare false, (b) other characters are replaced with an element of whitespace according to their last nibble so will compare equal only if they are that whitespace character.

    I’m not sure how easy it would be to do such tricks with vgather.vv. In particular, the length of the input doesn’t matter (could be longer) but the length of white space must be 16 bytes. I’m not sure how the whole vlen stuff interacts with tricks like this where you (a) require certain fixed lengths and (b) may have different lengths for tables and input vectors. (and indeed there might just be better ways, eg you could imagine an operation with a 256-bit register where you permute some vector of bytes by sign-extending the nth bit of the 256-bit register into the result where the input byte is n).

  • Codebases to read
    5 projects | /r/cpp | 5 Dec 2023
    Additionally, if you like low level stuff, check out libfmt ( - not a big project, not difficult to understand. Or something like simdjson (
  • Building a high performance JSON parser
    19 projects | | 5 Nov 2023
    Everything you said is totally reasonable. I'm a big fan of napkin math and theoretical upper bounds on performance.

    simdjson ( claims to fully parse JSON on the order of 3 GB/sec. Which is faster than OP's Go whitespace parsing! These tests are running on different hardware so it's not apples-to-apples.

    The phrase "cannot go faster than this" is just begging for a "well ackshully". Which I hate to do. But the fact that there is an existence proof of Problem A running faster in C++ SIMD than OP's Probably B scalar Go is quite interesting and worth calling out imho. But I admit it doesn't change the rest of the post.

    19 projects | | 5 Nov 2023
    The walkthrough is very nice, how to do this if you're going to do it.

    If you're going for pure performance in a production environment you might take a look at Daniel Lemire's work: Or the MinIO port of it to Go:

    19 projects | | 5 Nov 2023
  • New package : lspce - a simple LSP Client for Emacs
    4 projects | /r/emacs | 30 Jun 2023
    I have same question as /u/JDRiverRun : how do you deal with JSON, do you parse json on Rust side or on Emacs side. I see that you are requiring json.el in your lspce.el, but I haven't looked through entire file carefully. If you parse on Rust side, do you use simdjson (there are at least two Rust bindings to it)? If yes, what are your impressions, experiences compared to more "standard" json library?
  • Any fresh jvm21 benchmarks ?
    2 projects | /r/java | 21 May 2023
    I expect a lot of transcoders will be rewritten when the Vector instructions land. You can see speedups when used in other languages, such as simdjson. Please try to be more thoughtful and not disregard other people's hard work so easily.
  • Why is there no reliable way to receive signal when OOM killer decides to kill you
    3 projects | /r/linux | 15 Apr 2023
    You will never make 150GB/s though. Not even close. For example, simdjson achieves 3GB/s and is by far the fastest JSON parser out there.
  • I made JSON.parse() 2x faster
    4 projects | /r/programming | 6 Mar 2023
    Would you consider SIMD operations parallel?
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