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HTTP/2 State-Machine based protocol implementation

Project description

This repository contains a pure-Python implementation of a HTTP/2 protocol stack. It’s written from the ground up to be embeddable in whatever program you choose to use, ensuring that you can speak HTTP/2 regardless of your programming paradigm.

You use it like this:

import h2.connection

conn = h2.connection.H2Connection()
conn.send_headers(stream_id=stream_id, headers=headers)
conn.send_data(stream_id, data)
events = conn.receive_data(socket_data)

This repository does not provide a parsing layer, a network layer, or any rules about concurrency. Instead, it’s a purely in-memory solution, defined in terms of data actions and HTTP/2 frames. This is one building block of a full Python HTTP implementation.

To install it, just run:

pip install h2


Documentation is available at


hyper-h2 welcomes contributions from anyone! Unlike many other projects we are happy to accept cosmetic contributions and small contributions, in addition to large feature requests and changes.

Before you contribute (either by opening an issue or filing a pull request), please read the contribution guidelines.


hyper-h2 is made available under the MIT License. For more details, see the LICENSE file in the repository.


hyper-h2 is maintained by Cory Benfield, with contributions from others. For more details about the contributors, please see CONTRIBUTORS.rst.

Release History

1.1.1 (2015-11-17)


  • Forcibly lowercase all header names to improve compatibility with implementations that demand lower-case header names.

1.1.0 (2015-10-28)

API Changes (Backward-Compatible)

  • Added a new ConnectionTerminated event, which fires when GOAWAY frames are received.
  • Added a subclass of NoSuchStreamError, called StreamClosedError, that fires when actions are taken on a stream that is closed and has had its state flushed from the system.
  • Added StreamIDTooLowError, raised when the user or the remote peer attempts to create a stream with an ID lower than one previously used in the dialog. Inherits from ValueError for backward-compatibility reasons.


  • Do not throw ProtocolError when attempting to send multiple GOAWAY frames on one connection.
  • We no longer forcefully change the decoder table size when settings changes are ACKed, instead waiting for remote acknowledgement of the change.
  • Improve the performance of checking whether a stream is open.
  • We now attempt to lazily garbage collect closed streams, to avoid having the state hang around indefinitely, leaking memory.
  • Avoid further per-stream allocations, leading to substantial performance improvements when many short-lived streams are used.

1.0.0 (2015-10-15)

  • First production release!

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