---
id: cyseq
version: "0.1.3"
license: Apache-2.0
license_treatment: permissive
maintenance: active
---

# cyseq — "A Cython version of ScanCode-toolkit's licensedcode.seq"

License: permissive · Maintenance: active · Downloads: 81.5K/mo

## What it is and what it does

cyseq is a Cython-compiled library that accelerates sequence matching and comparison operations originally developed as part of ScanCode-toolkit's license detection engine. It takes computationally intensive sequence algorithms and compiles them to C for faster execution, making it suitable for applications that perform repeated or large-scale text comparison tasks.

The package targets developers working with license detection, text similarity analysis, or other sequence-based matching problems where the pure-Python implementation would be a bottleneck. It has no runtime dependencies beyond Python itself and is distributed as pre-built wheels for Python 3.10+ across major platforms, reducing installation complexity.

Use it for:

- Accelerating license text matching in software composition analysis or compliance tools.
- Speeding up sequence comparison operations in large-scale text processing pipelines.
- Replacing the pure-Python ScanCode licensedcode.seq module in performance-sensitive applications.
- Embedding optimized sequence matching in tools that analyze code or document similarity at scale.

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

cyseq provides a Cython-optimized implementation of sequence matching and comparison operations originally from ScanCode-toolkit's licensedcode module, designed for performance-critical text processing tasks.

Yes, if you need the specific sequence operations cyseq provides and performance is a concern. The package is actively maintained, carries a permissive license, has no external dependencies, and offers pre-built wheels for common environments. However, verify that its API matches your use case and that the performance gain justifies the compiled-dependency overhead for your workload.

## Install

pip install cyseq
uv add cyseq
poetry add cyseq

## Installing cyseq

Before you install: Medium install friction due to compiled wheels for multiple Python versions and platforms. The package is actively maintained with recent commits and carries a permissive Apache-2.0 license, though it is early in its release history (first released 2025-07-31).

License in practice: Apache-2.0 is permissive and imposes minimal restrictions on use, modification, and distribution. You may use this in commercial or proprietary projects with only attribution requirements.

Quickstart:

pip install cyseq

import cyseq
# Use sequence matching operations from the module

Requires Python 3.10 or later. Pre-built wheels are available for common platforms (macOS, Linux, Windows) and architectures (x86_64, aarch64).

Verify before relying:

- What specific sequence operations or APIs does cyseq expose beyond the original ScanCode implementation?
- Performance improvement magnitude compared to the pure-Python ScanCode version.
- Whether this is intended as a drop-in replacement or requires API changes in calling code.

## Package facts

- License: Apache-2.0 (permissive)
- Python support: supports_current
- Install friction: medium
- Maintenance: active
- Downloads: 81.5K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

cython sequence matching, optimized text comparison, license code sequence, fast sequence operations, scancode licensedcode, cython text processing, sequence alignment library, cython-compiled, performance-optimization, text-processing

[View on SkillFed](https://skillfed.io/packages/cyseq) · [View on PyPI](https://pypi.org/project/cyseq/)