denoland/std

> The Deno Standard Library — audited, web-standards-first building blocks, > published as independent @std/* packages on JSR.

GitHub repo · Official website · License: MIT

Overview

denoland/std (formerly deno_std; the old name still redirects) is the standard library for the Deno runtime, started in November 2018 alongside Deno itself. It fills the gap between Deno's deliberately small built-in API surface and what real programs need: paths, filesystem helpers, HTTP utilities, assertions, CSV/YAML/TOML/JSONC parsing, encoding, async primitives, CLI argument parsing, semver, UUIDs, streams — each shipped as its own semver'd package (@std/path, @std/assert, @std/csv, ...).

The library has lived through two identity shifts. Early std imitated Go's standard library — including Go-style Reader/Writer I/O interfaces — and was imported by URL from deno.land/std@0.x/, versioned as one monolithic 0.x release train. Around 2024 both decisions were reversed: the I/O layer was rebuilt on Web Streams and other web standards[^2], and distribution moved to JSR with per-package semantic versioning; deno.land/std was frozen at 0.224.0[^1]. The first wave of packages reached stable 1.0.0 in 2024[^3].

The 3.5k GitHub stars badly understate reach: std is a default dependency of most non-trivial Deno code, and JSR's @std scope is among the most-downloaded on the registry. Maintenance is healthy — pushes within days of writing and ~300 open issues under active triage by paid Deno company staff, not volunteers.

Getting Started

# Deno
deno add jsr:@std/assert jsr:@std/path

# Node.js / Bun (via JSR's npm compatibility layer)
npx jsr add @std/path

import { assertEquals } from "@std/assert";
import { join } from "@std/path";
import { delay } from "@std/async";

Deno.test("join builds platform-correct paths", async () => {
  await delay(10);
  assertEquals(join("users", "brad"), "users/brad");
});

Run with deno test. On Node/Bun, packages that only use web-standard APIs work as normal npm imports.

Architecture / How It Works

The repo is a monorepo where each top-level directory is one independently versioned JSR package with its own deno.json. Design rules are written down in an in-repo architecture guide[^2] and enforced in review:

Web standards first. APIs are built on ReadableStream, Uint8Array,

URL, AbortSignal — not runtime-specific primitives. The Go-derived Reader/Writer interfaces of early std were removed in the pre-1.0 cleanup.

Fine-grained modules. Most functions live in single-export files

(@std/path/join, @std/collections/chunk), so bundlers tree-shake well and you can import one function without pulling a kitchen sink.

Minimal coupling. Inter-package dependencies are kept few and explicit;

there is no shared "internal utils" grab bag exposed to users.

Stability tiers. Packages at >=1.0.0 follow strict semver; sub-1.0

packages (e.g. @std/log, @std/datetime for long stretches) follow a documented 0.x breaking-change convention[^4] and can churn between minors.

Runtime portability is per-package. JSR displays compatibility per

package. Anything touching the Deno.* namespace is Deno-only; pure-web-standard packages run on Node, Bun, browsers, and edge runtimes.

Test coverage is tracked publicly per package[^5]; stable packages require near-complete coverage plus documented examples on every exported symbol.

Production Notes

The URL-import era is over. deno.land/std serves nothing newer than

0.224.0[^1]. Old URLs keep resolving, but fixes land only on JSR; codebases on https://deno.land/std@0.x/... imports face a mechanical but tedious migration to jsr:@std/* specifiers.

Pre-1.0 history means old tutorials lie. Years of 0.x breaking changes:

std/http's serve() removed in favor of built-in Deno.serve; std/node moved into the Deno CLI; std/flags became @std/cli's parseArgs; std/testing/asserts became @std/assert. Assume any std snippet from before 2024 is stale until checked against JSR docs.

Mixed versions are normal, pin them anyway. Per-package semver means one

project legitimately holds @std/path@1.x next to @std/log@0.x. Commit the lockfile; sub-1.0 packages can break on minor bumps.

Node/Bun usage works but read the compat badge. JSR transpiles @std/*

for npm consumers, and web-standard packages behave identically. Packages that reach for Deno.* fail outside Deno — and the failure is late (call time), not at install time.

Don't reimplement what the runtime absorbed. Deno has steadily pulled std

functionality into the CLI (serve, Node compat). Check whether a built-in exists before adding the std package; the std team itself deprecates in that direction.

When to Use / When Not

Use when:

You write Deno code at all — std is the sanctioned first stop before any

third-party dependency.

You want coverage-tested parsing (CSV, YAML, TOML, JSONC), encoding, or path

handling instead of picking among npm micro-packages.

You need cross-runtime utilities built on web standards that behave the same

in Deno, Node, Bun, and edge workers.

Avoid when:

You target Node exclusively — Node's own core modules plus established npm

libraries have deeper ecosystem support, and JSR adds an indirection layer.

You need a package still at 0.x and can't absorb breaking minor releases.
You need what std deliberately excludes (ORMs, frameworks, heavy date math).

Alternatives

nodejs/node — when targeting Node only, its built-in node: core modules

cover most of the same ground with zero dependencies.

es-toolkit/es-toolkit — broader general-purpose utility belt (lodash

successor) when you need collection/function helpers beyond std's scope.

date-fns/date-fns — full-featured date manipulation; @std/datetime is thin

and long sat below 1.0.

unjs/pathe — drop-in cross-runtime path utilities when you want npm-native

distribution rather than JSR.

History

| Version | Date | Notes | |---------|------|-------| | repo created | 2018-11 | Started alongside pre-1.0 Deno; Go-stdlib-inspired design. | | 0.x train | 2019–2024 | Monolithic versioning, URL imports from deno.land/std, frequent breaking changes. | | JSR migration | 2024 | Split into per-package @std/* on JSR, independent semver[^3]. | | 0.224.0 | 2024 | Final release published to deno.land/std; URL distribution frozen[^1]. | | @std 1.0.0 | 2024 | First wave of packages stabilized under strict semver[^3]. |

References

[^1]: denoland/std README — "Newer versions ... hosted on JSR. Older versions up till 0.224.0 are still available at deno.land/std." https://github.com/denoland/std [^2]: Deno Standard Library architecture guide. https://github.com/denoland/std/blob/main/.github/ARCHITECTURE.md [^3]: JSR @std scope — per-package versions and stability status. https://jsr.io/@std [^4]: Pre-1.0 versioning follows the semver <1.0.0 proposal. https://github.com/semver/semver/pull/923 [^5]: Deno std test coverage explorer. https://std-coverage.deno.dev/

Wiki: denoland/std