Parsing JSON at the speed of memory

Parsing gigabytes of JSON per second

JSON is everywhere on the Internet. Servers spend a lot of time parsing it. We need a fresh approach.

$ brew install simdjson·$ apt install libsimdjson-dev·$ vcpkg install simdjson

quickstart.cpp

#include "simdjson.h"
using namespace simdjson;

int main() {
  ondemand::parser parser;
  padded_string json = padded_string::load("twitter.json");
  ondemand::document tweets = parser.iterate(json);
  std::cout << uint64_t(tweets["search_metadata"]["count"])
            << " results." << std::endl;
}

up to 25GB/s

Parsing throughput

25×

Faster than JSON for Modern C++

Why simdjson

Highlights

Fast

Over 4× faster than RapidJSON and 25× faster than JSON for Modern C++.

Easy

First-class, easy-to-use, and carefully documented APIs.

Strict

Full JSON and UTF-8 validation, lossless parsing. Performance with no compromises.

Automatic

Selects a CPU-tailored parser at runtime. No configuration needed.

Reliable

From memory allocation to error handling, simdjson's design avoids surprises.

Peer Reviewed

Research published in VLDB Journal and Software: Practice and Experience.

Get started

Three lines from install to parse

simdjson ships as a header-only library and is packaged everywhere — Ubuntu, Debian, Fedora, Arch, Alpine, FreeBSD, Homebrew, vcpkg, conan, MSYS2. Drop it in, point it at JSON, get blazing fast results.

Quick start guide API reference

Prefer a dependency-free drop-in? Grab the amalgamated release, then add simdjson.h and simdjson.cpp straight to your C++ project — no package manager, no build system required. Download singleheader.zip

install.sh

# macOS
$ brew install simdjson

# Ubuntu / Debian
$ apt install libsimdjson-dev

# vcpkg
$ vcpkg install simdjson

Features

25 GB/s

On-Demand API

A radically new approach to parsing JSON documents at memory speed.

build

Build JSON

Generate JSON strings at gigabytes per second. Read more →

12 GB/s

Minify

Strip whitespace from JSON streams without parsing. Read more →

30 GB/s

UTF-8 Validation

Standalone validation that's faster than memcpy on some workloads. Read more →

3.5 GB/s

Multithreaded NDJSON

Crunch gigantic newline-delimited JSON streams at multi-GB/s. Read more →

query

JSON Pointer & JSONPath

Drill into a document by path without unboxing the whole thing. Read more →

safe

Errors, your way

Pick exceptions or error codes. Compile with or without exceptions. Read more →

auto

Runtime dispatch

Detects AVX-512, AVX2, NEON, RISC-V, Loongarch, POWER — ships one binary. Read more →

C++26

Reflection & custom types

Plug in your own data types via tag_invoke or C++26 static reflection.

Used in production

Trusted by infrastructure that ships

simdjson powers JSON parsing inside engineering teams at the scale where every cycle counts.

Node.js ClickHouse Meta Velox Google Pax Microsoft FishStore Shopify Intel PCM Apache Doris StarRocks Dgraph Milvus WatermelonDB

And a dozen ports & bindings — Python, R, Ruby, PHP, C#, Rust, Swift, Go, Erlang, Lua, Haskell. See them all →