---
id: fast-query-parsers
version: "1.0.3"
license: unclear
license_treatment: permissive
maintenance: active
---

# fast-query-parsers — Ultra-fast query string and url-encoded form-data parsers

License: permissive · Maintenance: active · Downloads: 81.8K/mo

## 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 above — 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

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

- License: not declared (permissive)
- Python support: supports_current
- Install friction: medium
- Maintenance: active
- Downloads: 81.8K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

query string parser, url encoded form parser, fast query parsing, parse query parameters, url form data parsing, query string parsing library, rust query parser, query-parsing, performance-critical, rust-binding

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