pyahocorasick
pyahocorasick is a fast and memory efficient library for exact or approximate multi-pattern string search. With the ``ahocorasick.Automaton`` class, you can find multiple key string occurrences at once in some input text. You can use it as a plain dict-like Trie or convert a Trie to an automaton for efficient Aho-Corasick search. And pickle to disk for easy reuse of large automatons. Implemented in C and tested on Python 3.6+. Works on Linux, macOS and Windows. BSD-3-Cause license.
Decision gist · record as of 2026-08-14
Yes, if you need to match multiple fixed patterns in text efficiently. The C implementation, active maintenance, permissive license, and zero security vulnerabilities make it reliable. Medium install friction is offset by pre-built wheels and performance gains over pure-Python alternatives for large-scale matching. Not necessary for single-pattern or occasional searches.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires C compiler to build from source; Python 3.10+ required.
- Pre-built wheels available for common platforms.
- Medium install friction due to C compilation requirement, but actively maintained with recent release 109 days ago and 1122 GitHub stars.
License · maintenance · safety
BSD-3-Clause and Public-Domain (permissive) — BSD-3-Clause and Public-Domain license. Permissive treatment allows commercial and private use with minimal restrictions.
last release 2026-04-27 (109 days) · last repo commit 2026-04-27 · 1,122 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 5,979,577 downloads/mo, #1,997 on PyPI
Alternatives
Verify before relying
pip install pyahocorasick
import ahocorasick
automaton = ahocorasick.Automaton()
automaton.add_word('he', (0, 'he'))
automaton.add_word('she', (1, 'she'))
automaton.make_automaton()
for end_index, value in automaton.iter('she'):
print(end_index, value)- Whether approximate matching (mentioned in description) is fully implemented or only exact matching is production-ready
- Performance characteristics compared to other multi-pattern matching libraries in real-world scenarios
What it is and what it does
pyahocorasick is a C-based Python library implementing the Aho-Corasick string matching algorithm, allowing you to search for multiple keyword strings in text in a single pass. It exposes both a Trie data structure for dict-like key-value storage by string and a finalized automaton for efficient multi-pattern search. You build the automaton ahead of time, optionally pickle it to disk, then reuse it to search text repeatedly—making it suited for applications like intrusion detection, anti-virus scanning, or bioinformatics where you have a fixed set of patterns to match against variable input.
The library stores pattern prefixes efficiently in memory and guarantees similar worst-case and best-case runtime regardless of pattern count, depending mainly on input text size and match count. It supports both unicode and bytes, works on Python 3.10 and up, and is available as pre-built wheels for Linux, macOS, and Windows, though building from source requires a C compiler.
Use it for
- Scan DNA sequencing reads for known CRISPR guide sequences or genetic markers in bioinformatics pipelines
- Detect multiple malware signatures or intrusion patterns in network traffic or log files
- Find all occurrences of a dictionary of keywords in large text documents for content filtering or analysis
- Build a reusable index of product codes or identifiers to match against incoming transaction or inventory data
- Implement fast spell-checking or autocorrect by matching input against a pre-built dictionary of valid words
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes, if you need to match multiple fixed patterns in text efficiently.
The C implementation, active maintenance, permissive license, and zero security vulnerabilities make it reliable. Medium install friction is offset by pre-built wheels and performance gains over pure-Python alternatives for large-scale matching. Not necessary for single-pattern or occasional searches.
Install
pyahocorasick on PyPI
Before you install
Medium install friction due to C compilation requirement, but actively maintained with recent release 109 days ago and 1122 GitHub stars. Pre-built wheels available for Python 3.10+ on Linux, macOS, and Windows.
Requires C compiler to build from source; Python 3.10+ required. Pre-built wheels available for common platforms.
License in practice
BSD-3-Clause and Public-Domain license. Permissive treatment allows commercial and private use with minimal restrictions.
Quickstart
pip install pyahocorasick
import ahocorasick
automaton = ahocorasick.Automaton()
automaton.add_word('he', (0, 'he'))
automaton.add_word('she', (1, 'she'))
automaton.make_automaton()
for end_index, value in automaton.iter('she'):
print(end_index, value)Verify before relying
- Whether approximate matching (mentioned in description) is fully implemented or only exact matching is production-ready
- Performance characteristics compared to other multi-pattern matching libraries in real-world scenarios
Package facts
| License | BSD-3-Clause and Public-Domain permissive |
| Python support | Supports the current Python release >=3.10 |
| Install friction | Medium. Platform-specific wheel |
| Runtime dependencies | None |
| Maintenance | Actively maintained 109 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 5,979,577 / month, #1,997 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | Development Status :: 5 - Production/StableProgramming Language :: CProgramming Language :: Python :: 3Topic :: Software Development :: LibrariesTopic :: Text Editors :: Text Processing |
Evidence: pyahocorasick-2.3.1-cp310-cp310-macosx_10_9_universal2.whl; pyahocorasick-2.3.1-cp310-cp310-macosx_11_0_arm64.whl; pyahocorasick-2.3.1-cp310-cp310-manylinux2014_aarch64.manylinux_2_17_aarch64.whl; pyahocorasick-2.3.1-cp310-cp310-manylinux2014_x86_64.manylinux_2_17_x86_64.whl; pyahocorasick-2.3.1-cp310-cp310-musllinux_1_2_aarch64.whl; pyahocorasick-2.3.1-cp310-cp310-musllinux_1_2_x86_64.whl; pyahocorasick-2.3.1-cp310-cp310-win_amd64.whl; pyahocorasick-2.3.1-cp311-cp311-macosx_10_9_universal2.whl; pyahocorasick-2.3.1-cp311-cp311-macosx_11_0_arm64.whl; pyahocorasick-2.3.1-cp311-cp311-manylinux2014_aarch64.manylinux_2_17_aarch64.whl; pyahocorasick-2.3.1-cp311-cp311-manylinux2014_x86_64.manylinux_2_17_x86_64.whl; pyahocorasick-2.3.1-cp311-cp311-musllinux_1_2_aarch64.whl; pyahocorasick-2.3.1-cp311-cp311-musllinux_1_2_x86_64.whl; pyahocorasick-2.3.1-cp311-cp311-win_amd64.whl; pyahocorasick-2.3.1-cp312-cp312-macosx_10_13_universal2.whl; pyahocorasick-2.3.1-cp312-cp312-macosx_11_0_arm64.whl; pyahocorasick-2.3.1-cp312-cp312-manylinux2014_aarch64.manylinux_2_17_aarch64.whl; pyahocorasick-2.3.1-cp312-cp312-manylinux2014_x86_64.manylinux_2_17_x86_64.whl; pyahocorasick-2.3.1-cp312-cp312-musllinux_1_2_aarch64.whl; pyahocorasick-2.3.1-cp312-cp312-musllinux_1_2_x86_64.whl
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See also ahocorapy · ahocorasick-rs · textsearch · flashtext · retrie · marisa-trie · PyTrie · pysimstring · immutables · paragraphs