# Kotlin/kotlinx-io

Kotlin multiplatform I/O library

Repository: https://github.com/Kotlin/kotlinx-io
Canonical: https://ross.abutalabs.com/products/kotlinx-io
Language: Kotlin
License: Apache-2.0
License Family: permissive
Topics: kotlin, kotlinx, io
Last push: 2026-08-05T19:54:06+00:00

## Health v2 (maintenance only)
Score: 86/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 96, release rhythm 66, longevity 100
- inputs: {"age_days": 3255, "days_push": 28, "days_rel": 68, "gap_med": 99, "n_releases_24m": 8}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1545, forks 82 (observed 2026-08-28T04:05:01.517004+00:00)

## What it is
kotlinx-io is a Kotlin multiplatform library providing basic I/O primitives such as Buffer, Source, Sink, and ByteString, inspired by Okio. It also offers experimental filesystem support with a multiplatform FileSystem and Path API.

## Use cases
- read and write bytes across JVM, native, and JS targets with one API
- efficiently buffer and copy byte data without extra allocations
- perform file and directory operations in Kotlin multiplatform code
- migrate or interoperate with Okio-based code via the bridge module
- build multiplatform network or serialization libraries on top of Source/Sink abstractions

## When to choose
- you need consistent I/O primitives across all Kotlin multiplatform targets
- you want segment-based buffers with cheap copies and minimal allocations
- you are building a Kotlin multiplatform library that needs file or byte-stream access

## When to avoid
- you need a fully stable, guaranteed-non-breaking API (the library is Alpha)
- you already use Okio and do not need multiplatform coverage
- you need advanced filesystem features beyond basic operations

## Facets
- artifact type: library
- maturity: experimental
- function: file-system, serialization, developer-tools
- domain: developer-tools, cross-platform, files
- platform: cross-platform, jvm, windows, wasm
- tags: kotlin-multiplatform, buffer, okio-inspired, byte-manipulation, jetbrains, android, ios, macos, linux

## Member repositories
- Kotlin/kotlinx-io (main) score 86

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:05:01.517004+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T04:30:34.969626+00:00, confidence not recorded.
  - readme: https://github.com/Kotlin/kotlinx-io (fetched 2026-08-28T04:05:01.517004+00:00, sha d9ad210cd23d)
- Data as of 2026-08-30T08:39:29.467469+00:00.