strictyaml
Strict, typed YAML parser
Decision gist · record as of 2026-08-14
Yes, if you need safe, schema-validated YAML parsing with clear errors. The low install friction, permissive MIT license, and wide adoption make it a solid choice. However, note the aging maintenance status—last release was 2023-03-10—so verify compatibility with your Python version and consider whether the lack of recent updates matters for your use case.AI-flagged interpretation of the facts on this page — verify before relying
Before you install
- Requires Python 3.7.0 or later.
- Low install friction with a single runtime dependency.
- Maintenance status is aging—last release was 2023-03-10, though the repository remains active and the package is widely used.
License · maintenance · safety
MIT (permissive) — MIT license is permissive, allowing free use, modification, and distribution with minimal restrictions—suitable for both open-source and commercial projects.
last release 2023-03-10 (1253 days) · last repo commit 2025-05-23 · 1,622 stars
0 known vulnerabilities (OSV.dev, 2026-08-14) · 31,485,597 downloads/mo, #786 on PyPI
Alternatives
Verify before relying
pip install strictyaml
from strictyaml import load, Map, Str, Int, Seq
schema = Map({"name": Str(), "age": Int(), "items": Seq(Str())})
person = load("name: Ford\nage: 42\nitems:\n- Towel", schema)
print(person.data)- Whether the aging maintenance status affects compatibility with current Python versions or ecosystem changes.
- Performance characteristics compared to standard YAML parsers for large documents or high-throughput scenarios.
What it is and what it does
StrictYAML is a YAML parser that enforces a restricted, safer subset of the YAML specification and validates parsed data against a schema you define. Unlike standard YAML parsers, it rejects implicit type coercion, anchors, aliases, and other features that make YAML hard to read or potentially unsafe. It parses YAML into strings, lists, and OrderedDicts by default, then casts to typed values only when you provide a schema using validators like Str(), Int(), Seq(), and Map().
The parser provides detailed error messages with line numbers and code snippets when validation fails. It also supports round-tripping: you can read YAML, modify it programmatically, and write it back out with comments and formatting preserved. This makes it useful for configuration files, data validation, and any scenario where you want predictable, type-safe YAML handling without the surprising behavior of standard YAML.
Use it for
- Parsing application configuration files with schema validation to catch typos or missing required keys early.
- Reading and modifying YAML documents while preserving comments and structure for round-trip editing.
- Building CLI tools that accept YAML input and need clear, line-numbered error messages for invalid data.
- Validating structured data such as test fixtures or deployment manifests against a predefined schema.
- Replacing standard YAML parsers in projects where implicit type coercion causes bugs or security concerns.
Worth the install?
AI-flagged interpretation of the facts on this page. Verify before relying on it.
Yes, if you need safe, schema-validated YAML parsing with clear errors.
The low install friction, permissive MIT license, and wide adoption make it a solid choice. However, note the aging maintenance status—last release was 2023-03-10—so verify compatibility with your Python version and consider whether the lack of recent updates matters for your use case.
Install
strictyaml on PyPI
Before you install
Low install friction with a single runtime dependency. Maintenance status is aging—last release was 2023-03-10, though the repository remains active and the package is widely used.
Requires Python 3.7.0 or later.
License in practice
MIT license is permissive, allowing free use, modification, and distribution with minimal restrictions—suitable for both open-source and commercial projects.
Quickstart
pip install strictyaml
from strictyaml import load, Map, Str, Int, Seq
schema = Map({"name": Str(), "age": Int(), "items": Seq(Str())})
person = load("name: Ford\nage: 42\nitems:\n- Towel", schema)
print(person.data)Verify before relying
- Whether the aging maintenance status affects compatibility with current Python versions or ecosystem changes.
- Performance characteristics compared to standard YAML parsers for large documents or high-throughput scenarios.
Package facts
| License | MIT permissive |
| Python support | Supports the current Python release >=3.7.0 |
| Install friction | Low. Pure-Python wheel |
| Runtime dependencies | 1 packagepython-dateutil |
| Maintenance | Aging 1,253 days since the last release |
| Last repo commit | |
| First released | |
| Downloads | 31,485,597 / month, #786 on PyPI 30-day window, as of 2026-08-14 |
| Known vulnerabilities | None known OSV.dev, checked 2026-08-14 |
| Classifiers | License :: OSI Approved :: MIT LicenseNatural Language :: EnglishProgramming Language :: Python :: 3Topic :: Software Development :: LibrariesTopic :: Text Processing :: Markup |
Evidence: strictyaml-1.7.3-py3-none-any.whl
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See also rapidyaml · yamale · yaml-rs · pykwalify · annotatedyaml · parse-errors · schema · ruyaml · ruamel.yaml · yamlcore