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Deno Standard Library

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High-quality APIs for Deno and the web. Use fearlessly.

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import { copy } from "";

await copy("./foo", "./bar");

See here for recommended usage patterns.


Check out the documentation here.

  1. Include the version of the library in the import specifier.


    import { copy } from "";
  2. Only import modules that you require.

    Bad (when using only one function):

    import * as fs from "";

    Good (when using only one function):

    import { copy } from "";

    Good (when using multiple functions):

    import * as fs from "";
  3. Do not import symbols with an underscore in the name.


    import { _format } from "";
  4. Do not import modules with an underscore in the path.


    import { filterInPlace } from "";
  5. Do not import test modules or test data.


    import { test } from "";


Sub-module Status
archive Unstable
assert Stable
async Stable
bytes Stable
cli Unstable
collections Stable
console Unstable
crypto Stable
csv Stable
data_structures Unstable
datetime Unstable
dotenv Unstable
encoding Stable
expect Unstable
flags Unstable
fmt Stable
front_matter Stable
fs Stable
html Unstable
http Unstable
ini Unstable
io Unstable
json Stable
jsonc Stable
log Unstable
media_types Stable
msgpack Unstable
net Unstable
path Stable
permissions Deprecated
regexp Unstable
semver Unstable
streams Stable
testing Stable
text Unstable
toml Stable
ulid Unstable
url Unstable
uuid Stable
webgpu Unstable
yaml Stable

For background and discussions regarding the stability of the following sub-modules, see #3489.


Minimal Exports

Files are structured to minimize the number of dependencies they incur and the amount of effort required to manage them, both for the maintainer and the user. In most cases, only a single function or class, alongside its related types, are exported. In other cases, functions that incur negligible dependency overhead will be grouped together in the same file.

Deprecation Policy

We deprecate the APIs in the Standard Library when they get covered by new JavaScript language APIs or new Web Standard APIs. These APIs are usually removed after 3 minor versions.

If you still need to use such APIs after the removal for some reason (for example, the usage in Fresh island), please use the URL pinned to the version where they are still available.

For example, if you want to keep using readableStreamFromIterable, which was deprecated and removed in favor of ReadableStream.from in v0.195.0, please use the import URL pinned to v0.194.0:

import { readableStreamFromIterable } from "";


Check out the contributing guidelines here.


The Standard Library is versioned independently of the Deno CLI. This will change once the Standard Library is stabilized. See here for the compatibility of different versions of the Deno Standard Library and the Deno CLI.

A new minor version of the Standard Library is published at the same time as every new version of the Deno CLI (including patch versions).


Built with the Deno Standard Library

<a href="">
    alt="Built with the Deno Standard Library"
[![Built with the Deno Standard Library](](