trio
A friendly Python library for async concurrency and I/O
Decision gist · record as of 2026-08-14
Yes. Trio is a mature, actively maintained async library with low install friction, permissive licensing, no known vulnerabilities, and strong community adoption. Install it if you need to write concurrent I/O code and prefer structured concurrency principles and a simpler API over asyncio. The only caveat is Python 3.10+ requirement; if you're on an older version, you cannot use it.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.10 or later (CPython or maintained PyPy3 versions); Linux, macOS, Windows, or FreeBSD.
- Low friction: pure Python dependencies on most platforms (cffi has wheels on Windows), wheel-based distribution, and actively maintained with a release 3 days old.
- The project is mature and well-tested since its 2017 initial release.
License · maintenance · safety
MIT OR Apache-2.0 (permissive) — Permissively licensed under MIT OR Apache-2.0, so you can choose the license that fits your project's legal requirements with no restrictions on commercial use.
last release 2026-08-11 (3 days) · last repo commit 2026-08-11 · 7,305 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 56,068,952 downloads/mo, #528 on PyPI
Alternatives
Verify before relying
pip install trio
import trio
async def main():
print('Hello from Trio')
await trio.sleep(0)
trio.run(main)- Whether the structured concurrency model is suitable for your specific concurrency patterns compared to asyncio.
- Performance characteristics under high-concurrency workloads relative to other async libraries.
- Ecosystem maturity of third-party libraries built on Trio versus asyncio alternatives.
What it is and what it does
Trio is a production-ready async I/O library designed from the ground up around async/await syntax and structured concurrency principles. It lets you write programs that handle multiple concurrent tasks—such as fetching many web pages in parallel, running a web server with simultaneous connections, or monitoring multiple subprocesses—without the complexity and pitfalls of older async approaches. The library emphasizes usability and correctness, aiming to make concurrent code easier to reason about and less error-prone.
The package depends on seven runtime libraries (attrs, sortedcontainers, idna, outcome, sniffio, cffi, exceptiongroup) and is actively maintained with recent releases. It supports Python 3.10 and later on CPython and PyPy, and runs on Linux, macOS, Windows, and FreeBSD. The project is mature, well-documented, and widely used in production; while minor interface adjustments occasionally occur, breaking changes are rare.
Use it for
- Build web spiders or scrapers that fetch many URLs concurrently without blocking.
- Write web servers that handle many simultaneous client connections and WebSocket streams.
- Implement process supervisors that monitor and manage multiple subprocesses in parallel.
- Create network applications that need to handle multiple concurrent I/O operations efficiently.
- Develop testing frameworks or tools that require concurrent task execution and coordination.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes.
Trio is a mature, actively maintained async library with low install friction, permissive licensing, no known vulnerabilities, and strong community adoption. Install it if you need to write concurrent I/O code and prefer structured concurrency principles and a simpler API over asyncio. The only caveat is Python 3.10+ requirement; if you're on an older version, you cannot use it.
Install
trio on PyPI
Before you install
Low friction: pure Python dependencies on most platforms (cffi has wheels on Windows), wheel-based distribution, and actively maintained with a release 3 days old. The project is mature and well-tested since its 2017 initial release.
Requires Python 3.10 or later (CPython or maintained PyPy3 versions); Linux, macOS, Windows, or FreeBSD.
License in practice
Permissively licensed under MIT OR Apache-2.0, so you can choose the license that fits your project's legal requirements with no restrictions on commercial use.
Quickstart
pip install trio
import trio
async def main():
print('Hello from Trio')
await trio.sleep(0)
trio.run(main)Verify before relying
- Whether the structured concurrency model is suitable for your specific concurrency patterns compared to asyncio.
- Performance characteristics under high-concurrency workloads relative to other async libraries.
- Ecosystem maturity of third-party libraries built on Trio versus asyncio alternatives.
Package facts
| License | MIT OR Apache-2.0 permissive |
| Python support | Supports the current Python release >=3.10 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 7 packagesattrssortedcontainersidnaoutcomesniffiocffiexceptiongroup |
| Maintenance | Actively maintained 3 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 56,068,952 / month, #528 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 4 - BetaFramework :: TrioIntended Audience :: DevelopersOperating System :: MacOS :: MacOS XOperating System :: Microsoft :: WindowsOperating System :: POSIX :: BSDOperating System :: POSIX :: LinuxProgramming Language :: Python :: 3 :: OnlyProgramming Language :: Python :: 3.10Programming Language :: Python :: 3.11Programming Language :: Python :: 3.12Programming Language :: Python :: 3.13Programming Language :: Python :: 3.14Programming Language :: Python :: Implementation :: CPythonProgramming Language :: Python :: Implementation :: PyPyTopic :: System :: NetworkingTyping :: Typed |
Evidence: trio-0.34.0-py3-none-any.whl
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See also anyio · pytest-trio · sniffio · aiometer · duet · asyncgui · outcome · trio-websocket · trio-typing · aiopath