fast-query-parsers

What it is and what it does

fast-query-parsers is a Python library that wraps Rust-based parsers for two common web tasks: parsing query strings into key-value tuples and parsing URL-encoded form data into Python dictionaries with automatic type conversion. It is designed as a drop-in replacement for the standard library's parse_qsl and parse_qs functions, but with significantly faster performance. The library supports Python 3.8 and later and is actively used by Litestar, a web framework, though it can be used independently in any project that needs to parse query parameters or form data.

The main value proposition is speed: according to the documentation's benchmarks, query string parsing is more than 5 times faster than the standard library, and URL-encoded parsing is more than 2 times faster. The URL-encoded parser also handles type conversions correctly—parsing numbers, booleans, JSON arrays, and objects—unlike the standard library's parse_qs, which nests all values in lists. It has no runtime dependencies and is available as pre-compiled wheels for most common platforms.

Use it for:

• Parsing incoming HTTP query parameters in high-throughput web applications where parsing latency matters.
• Converting URL-encoded form submissions into typed Python dictionaries without manual post-processing.
• Replacing standard library parsing in existing web frameworks or ASGI applications to reduce CPU overhead.
• Handling JSON-like values embedded in query strings or form fields (arrays, objects, booleans, null).

Worth the install?

AI-flagged interpretation of the facts on this page — verify before relying

Parses query strings and URL-encoded form data into Python objects using Rust-based parsers, offering significantly faster performance than the standard library.

Yes, if you are building or maintaining a web application that parses query strings or form data at scale. The performance gains are substantial and well-documented, the library is actively maintained, has no external dependencies, and carries a permissive MIT license. Install friction is moderate due to compiled wheels, but pre-built binaries cover standard platforms. Not necessary for low-traffic applications where parsing is not a bottleneck.

Install

fast-query-parsers on PyPI

pip install fast-query-parsers

uv add fast-query-parsers

poetry add fast-query-parsers

Installing fast-query-parsers

Before you install

Medium install friction due to compiled wheels, but pre-built binaries are available for common platforms (x86_64, ARM, PowerPC, s390x on Linux, macOS, and Windows). Active maintenance with last commit on 2026-07-30.

License in practice

Licensed under MIT (permissive), allowing use in both open-source and proprietary projects with minimal restrictions.

Quickstart

from fast_query_parsers import parse_query_string, parse_url_encoded_dict

# Parse query string
result = parse_query_string(b"value=1&value=2&type=dollar", "&")
# [("value", "1"), ("value", "2"), ("type", "dollar")]

# Parse URL-encoded form data
encoded = b"value=10&healthy=true&json=null"
result = parse_url_encoded_dict(encoded, parse_numbers=True)
# {"value": 10, "healthy": True, "json": None}

Verify before relying

• Whether the x5 and x2 performance improvements cited in benchmarks hold for real-world workloads in production environments.
• Compatibility with edge cases in query string encoding or malformed input beyond what the documentation examples show.

Package facts

Evidence: fast_query_parsers-1.0.3-cp38-abi3-macosx_10_7_x86_64.whl; fast_query_parsers-1.0.3-cp38-abi3-macosx_10_9_x86_64.macosx_11_0_arm64.macosx_10_9_universal2.whl; fast_query_parsers-1.0.3-cp38-abi3-manylinux_2_17_aarch64.manylinux2014_aarch64.whl; fast_query_parsers-1.0.3-cp38-abi3-manylinux_2_17_armv7l.manylinux2014_armv7l.whl; fast_query_parsers-1.0.3-cp38-abi3-manylinux_2_17_ppc64le.manylinux2014_ppc64le.whl; fast_query_parsers-1.0.3-cp38-abi3-manylinux_2_17_ppc64.manylinux2014_ppc64.whl; fast_query_parsers-1.0.3-cp38-abi3-manylinux_2_17_s390x.manylinux2014_s390x.whl; fast_query_parsers-1.0.3-cp38-abi3-manylinux_2_17_x86_64.manylinux2014_x86_64.whl; fast_query_parsers-1.0.3-cp38-abi3-manylinux_2_5_i686.manylinux1_i686.whl; fast_query_parsers-1.0.3-cp38-abi3-musllinux_1_2_aarch64.whl; fast_query_parsers-1.0.3-cp38-abi3-musllinux_1_2_armv7l.whl; fast_query_parsers-1.0.3-cp38-abi3-musllinux_1_2_i686.whl; fast_query_parsers-1.0.3-cp38-abi3-musllinux_1_2_x86_64.whl; fast_query_parsers-1.0.3-cp38-abi3-win32.whl; fast_query_parsers-1.0.3-cp38-abi3-win_amd64.whl

Keywords: query, query string, qs, query parameters, rust, asgi, starlite, litestar, parser

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