zodrs

Drop-in blazingly-fast replacement for Zod with a Rust validation core.

Benchmarks • Behavior contract • Divergences • Dependency rationale

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What this is

zodrs keeps the Zod v4 TypeScript surface and replaces the validation engine. Schemas compile to a flat plan arena that a Rust core walks over raw JSON bytes in one pass. The backends are designed to agree, and the conformance suite runs four of them against the same corpus, so the engine underneath is an implementation detail you can switch off.

Correctness is measured against Zod's own v4.4.3 test corpus, vendored into packages/conformance. Every departure is recorded in packages/conformance/EXCISIONS.md; anything failing that was not excised is a bug.

Install

npm install zod-rs

Requires Node 20.17 or later. The package embeds a prebuilt Linux x64 GNU N-API addon and a wasm32-wasip1-threads addon. On any other platform the loader skips the native tier and uses the embedded WASM addon; if that is unavailable too, validation falls back to the TypeScript validator.

Quickstart

import { z } from "zod-rs";

const User = z.object({
  name: z.string().min(3),
  age: z.number().int().positive(),
});

User.parse({ name: "Ada", age: 36 });
// -> { name: "Ada", age: 36 }

const result = User.safeParse({ name: "Al", age: -1 });
result.success; // false
result.error.issues.map((i) => [i.code, i.path]);
// -> [["too_small", ["name"]], ["too_small", ["age"]]]

To hand raw bytes straight to the Rust core, skip JSON.parse and call parseJson:

User.parseJson('{"name":"Ada","age":36}');

parseJson returns exactly what parse(JSON.parse(...)) returns. When no Rust backend is registered it does that internally.

Entry points

Import	Contents
zod-rs	Classic z surface
zod-rs/mini	Tree-shakeable functional surface
zod-rs/core	Shared primitives and issue types
zod-rs/locales	Error-message locales
zod-rs/v4, zod-rs/v4-mini, zod-rs/v4/core, zod-rs/v4/locales	Version-qualified aliases

Zod's v3 surface is not shipped.

Backends

Two independent switches select how validation runs. Both exist so the conformance suite can pin each tier against the corpus; neither is needed in normal use.

Variable	Values	Effect
ZODRS_LOADER	unset / native	Native N-API addon, then WASM, then none
	wasm	WASM addon only
	none	No Rust backend; TypeScript validator only
ZODRS_BACKEND	interpreter	Forces the tree-walking interpreter over compiled codegen

The suite runs all four lanes. Each passes 5,679 tests across 435 files.

Benchmarks

Measured against Zod v4.4.3 on the native tier, with valid inputs. Each figure is the median of three full runs. The harness lives in packages/bench; the comparison set is fixed in packages/bench/gate.mjs.

Suite	Workload per op	zodrs (ops/s)	zod4 (ops/s)	Ratio
z.string().parse	10,000 strings	34,252	1,875	18.27x
z.number().parse	10,000 numbers	8,116	1,570	5.17x
z.array().parse	1,000 arrays of 3 strings	12,217	4,188	2.92x
z.union().parse	1 value, 3-member union	3,438,230	1,495,908	2.30x
z.discriminatedUnion().parse	100 objects	87,666	39,411	2.22x
z.object().safeParse	1,000 3-field objects	15,740	7,251	2.17x
z.string().datetime().parse	10,000 ISO strings	820	441	1.86x
z.object() initialization	build 1,000 schemas	12	7	1.71x
z.object().parse	1,000 3-field objects	19,812	17,871	1.11x
safeParseJson	one 4 KB nested payload	21,433	21,699	0.99x

An op is a whole suite workload, not one value, and the workloads differ. Read each row across its two engine columns; do not compare rows to each other.

The safeParseJson row measures zodrs.safeParseJson(buffer) against zod4.safeParse(JSON.parse(json)). At 0.99x it is a tie, and it is the one cell of the release gate that did not pass on this run: the gate requires every comparison to reach at least 1.00x.

Reproduce the full gate with three runs into distinct directories, then the median-of-three comparison:

SUITES=object,object-safe,string,number,datetime,union,discriminated-union,array,init
for i in 1 2 3; do
  BENCH_RESULTS_DIR=/tmp/bench$i pnpm -C packages/bench run run "$SUITES"
done
node packages/bench/gate.mjs /tmp/bench1 /tmp/bench2 /tmp/bench3

Numbers above: Node 24.18.0, Linux x64, Xeon Gold 6138, Tinybench 6.1.3. Absolute throughput depends on the machine; rerun the gate on yours.

Repository layout

Path	Contents
packages/zodrs	The published TypeScript package
packages/conformance	Vendored Zod v4.4.3 corpus, the correctness oracle
packages/bench	Benchmarks and the release performance gate
crates/zodrs	Pure Rust validation engine, no napi dependency
crates/zodrs-node	N-API and WASI binding layer

Development

cargo build --workspace
cargo nextest run --workspace
cargo clippy --workspace --all-targets -- -D warnings
cargo fmt --all -- --check
cargo deny check bans licenses sources

pnpm install
pnpm -r build
pnpm -C packages/conformance test
pnpm exec oxlint --config .oxlintrc.json packages/

Pre-commit hooks run through lefthook. Install them once:

pnpm exec lefthook install

License

MIT