# aiosignal > aiosignal: a list of registered asynchronous callbacks - **URL**: https://www.freshcrate.ai/projects/aiosignal - **Author**: aiohttp team - **Category**: Frameworks - **Latest version**: `1.4.0` (2026-04-21) - **License**: Apache 2.0 - **Source**: https://github.com/aio-libs/aiosignal/actions - **Homepage**: https://github.com/aio-libs/aiosignal - **Language**: Python - **GitHub**: 163 stars, 21 forks - **Registry**: pypi (`aiosignal`) - **Tags**: `pypi` ## Description ========= aiosignal ========= .. image:: https://github.com/aio-libs/aiosignal/workflows/CI/badge.svg :target: https://github.com/aio-libs/aiosignal/actions?query=workflow%3ACI :alt: GitHub status for master branch .. image:: https://codecov.io/gh/aio-libs/aiosignal/branch/master/graph/badge.svg?flag=pytest :target: https://codecov.io/gh/aio-libs/aiosignal?flags[0]=pytest :alt: codecov.io status for master branch .. image:: https://badge.fury.io/py/aiosignal.svg :target: https://pypi.org/project/aiosignal :alt: Latest PyPI package version .. image:: https://readthedocs.org/projects/aiosignal/badge/?version=latest :target: https://aiosignal.readthedocs.io/ :alt: Latest Read The Docs .. image:: https://img.shields.io/discourse/topics?server=https%3A%2F%2Faio-libs.discourse.group%2F :target: https://aio-libs.discourse.group/ :alt: Discourse group for io-libs .. image:: https://badges.gitter.im/Join%20Chat.svg :target: https://gitter.im/aio-libs/Lobby :alt: Chat on Gitter Introduction ============ A project to manage callbacks in `asyncio` projects. ``Signal`` is a list of registered asynchronous callbacks. The signal's life-cycle has two stages: after creation its content could be filled by using standard list operations: ``sig.append()`` etc. After you call ``sig.freeze()`` the signal is *frozen*: adding, removing and dropping callbacks is forbidden. The only available operation is calling the previously registered callbacks by using ``await sig.send(data)``. For concrete usage examples see the `Signals section of the `Web Server Advanced ` chapter of the `aiohttp documentation`_. Installation ------------ :: $ pip install aiosignal Documentation ============= https://aiosignal.readthedocs.io/ License ======= ``aiosignal`` is offered under the Apache 2 license. Source code =========== The project is hosted on GitHub_ Please file an issue in the `bug tracker `_ if you have found a bug or have some suggestions to improve the library. .. _GitHub: https://github.com/aio-libs/aiosignal .. _aiohttp documentation: https://docs.aiohttp.org/ ## Recent releases | Version | Date | Urgency | Changes | | --- | --- | --- | --- | | `1.4.0` | 2026-04-21 | Low | Imported from PyPI (1.4.0) | | `v1.4.0` | 2025-07-03 | Low | Features -------- - Added decorator functionality to ``Signal`` as a convenient way to add a callback -- by ``@Vizonex``. `#699 `_ - Improved type safety by allowing callback parameters to be type checked (typing-extensions is now required for Python <3.13). Parameters for a ``Signal`` callback should now be defined like ``Signal[int, str]`` -- by @Vizonex and @Dreamsorcerer. `#699 `_, `#710 | | `v1.4.0` | 2025-07-03 | Low | Features -------- - Added decorator functionality to ``Signal`` as a convenient way to add a callback -- by ``@Vizonex``. `#699 `_ - Improved type safety by allowing callback parameters to be type checked (typing-extensions is now required for Python <3.13). Parameters for a ``Signal`` callback should now be defined like ``Signal[int, str]`` -- by @Vizonex and @Dreamsorcerer. `#699 `_, `#710 | | `v1.4.0` | 2025-07-03 | Low | Features -------- - Added decorator functionality to ``Signal`` as a convenient way to add a callback -- by ``@Vizonex``. `#699 `_ - Improved type safety by allowing callback parameters to be type checked (typing-extensions is now required for Python <3.13). Parameters for a ``Signal`` callback should now be defined like ``Signal[int, str]`` -- by @Vizonex and @Dreamsorcerer. `#699 `_, `#710 | | `v1.4.0` | 2025-07-03 | Low | Features -------- - Added decorator functionality to ``Signal`` as a convenient way to add a callback -- by ``@Vizonex``. `#699 `_ - Improved type safety by allowing callback parameters to be type checked (typing-extensions is now required for Python <3.13). Parameters for a ``Signal`` callback should now be defined like ``Signal[int, str]`` -- by @Vizonex and @Dreamsorcerer. `#699 `_, `#710 | | `v1.4.0` | 2025-07-03 | Low | Features -------- - Added decorator functionality to ``Signal`` as a convenient way to add a callback -- by ``@Vizonex``. `#699 `_ - Improved type safety by allowing callback parameters to be type checked (typing-extensions is now required for Python <3.13). Parameters for a ``Signal`` callback should now be defined like ``Signal[int, str]`` -- by @Vizonex and @Dreamsorcerer. `#699 `_, `#710 | | `v1.4.0` | 2025-07-03 | Low | Features -------- - Added decorator functionality to ``Signal`` as a convenient way to add a callback -- by ``@Vizonex``. `#699 `_ - Improved type safety by allowing callback parameters to be type checked (typing-extensions is now required for Python <3.13). Parameters for a ``Signal`` callback should now be defined like ``Signal[int, str]`` -- by @Vizonex and @Dreamsorcerer. `#699 `_, `#710 | | `v1.4.0` | 2025-07-03 | Low | Features -------- - Added decorator functionality to ``Signal`` as a convenient way to add a callback -- by ``@Vizonex``. `#699 `_ - Improved type safety by allowing callback parameters to be type checked (typing-extensions is now required for Python <3.13). Parameters for a ``Signal`` callback should now be defined like ``Signal[int, str]`` -- by @Vizonex and @Dreamsorcerer. `#699 `_, `#710 | | `v1.4.0` | 2025-07-03 | Low | Features -------- - Added decorator functionality to ``Signal`` as a convenient way to add a callback -- by ``@Vizonex``. `#699 `_ - Improved type safety by allowing callback parameters to be type checked (typing-extensions is now required for Python <3.13). Parameters for a ``Signal`` callback should now be defined like ``Signal[int, str]`` -- by @Vizonex and @Dreamsorcerer. `#699 `_, `#710 | | `v1.4.0` | 2025-07-03 | Low | Features -------- - Added decorator functionality to ``Signal`` as a convenient way to add a callback -- by ``@Vizonex``. `#699 `_ - Improved type safety by allowing callback parameters to be type checked (typing-extensions is now required for Python <3.13). Parameters for a ``Signal`` callback should now be defined like ``Signal[int, str]`` -- by @Vizonex and @Dreamsorcerer. `#699 `_, `#710 | ## Dependency audit - **Score**: 98/100 - **Total deps**: 0 - **Resolved**: 0 - **Unresolved**: 0 - **License conflicts**: 0 - **Warnings**: 1 - **Scanned**: 2026-05-18 ## Citation - HTML: https://www.freshcrate.ai/projects/aiosignal - Markdown: https://www.freshcrate.ai/projects/aiosignal.md - Dependencies JSON: https://www.freshcrate.ai/api/projects/aiosignal/deps _Generated by freshcrate.ai. Indexes pypi releases for AI-agent ecosystem packages._