# typetools/checker-framework

Pluggable type-checking for Java

Repository: https://github.com/typetools/checker-framework
Canonical: https://ross.abutalabs.com/products/checker-framework
Homepage: http://checkerframework.org/
Language: Java
License: NOASSERTION
License Family: other
Topics: java, types, verification
Last push: 2026-09-02T23:23:56+00:00

## Health v2 (maintenance only)
Score: 100/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 100, release rhythm 100, longevity 100
- inputs: {"age_days": 4079, "days_push": 0, "days_rel": 1, "gap_med": 28, "n_releases_24m": 28}
- flags: no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 1149, forks 437 (observed 2026-09-03T02:15:20.049984+00:00)

## What it is
The Checker Framework is a framework for pluggable type-checking in Java, enhancing Java's type system to detect and prevent bugs like null pointer exceptions, SQL injection, and concurrency errors at compile time. It ships with built-in compiler plug-in checkers (Nullness, Regex, Tainting, Resource Leak, etc.) and lets developers write their own custom checkers.

## Use cases
- find null pointer bugs in my Java code at compile time
- verify absence of SQL injection vulnerabilities in Java
- write a custom type checker as a javac plugin
- detect resource leaks in Java programs
- check regex syntax statically in Java
- add taint analysis to a Java build
- prevent concurrency errors in Java with static checking

## When to choose
- you want compile-time guarantees about Java program correctness
- you need to catch null pointer, leak, or taint bugs before runtime
- you want to build custom pluggable type checkers for Java
- you are doing formal verification or security analysis of Java code

## When to avoid
- your project is not written in Java
- you only need lightweight linting without type annotations
- you cannot modify source code to add type annotations
- you need dynamic/runtime verification rather than static checking

## Facets
- artifact type: framework
- maturity: stable
- function: type-system, testing, linter, compiler, security
- domain: programming-languages, developer-tools, security, compilers
- platform: jvm, cross-platform, cli
- tags: pluggable-types, static-analysis, nullness-checking, java-annotations, formal-verification, bug-detection

## Member repositories
- typetools/checker-framework (main) score 100

## Provenance
- Observed fields: from GitHub, fetched 2026-09-03T02:15:20.049984+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T06:33:52.814784+00:00, confidence not recorded.
  - readme: https://github.com/typetools/checker-framework (fetched 2026-09-03T02:15:20.049984+00:00, sha a6e0f2ab290a)
  - homepage: http://checkerframework.org/ (fetched 2026-08-29T12:39:17.905816+00:00, sha 398219164f8c)
  - site_page: https://checkerframework.org/manual (fetched 2026-08-29T12:39:17.908981+00:00, sha 96ef39555ecd)
  - site_page: https://checkerframework.org/annotation-file-utilities (fetched 2026-08-29T12:39:17.918195+00:00, sha ec9a1530fddd)
  - site_page: https://checkerframework.org/releases (fetched 2026-08-29T12:39:17.920360+00:00, sha 4cde459629b8)
- Data as of 2026-08-30T08:39:29.467469+00:00.