# uber/NullAway

A tool to help eliminate NullPointerExceptions (NPEs) in your Java code with low build-time overhead

Repository: https://github.com/uber/NullAway
Canonical: https://ross.abutalabs.com/products/nullaway
Language: Java
License: MIT
License Family: permissive
Topics: java, static-analysis, android, nullability, nullability-analysis, static-code-analysis
Last push: 2026-08-26T19:58:09+00:00

## Health v2 (maintenance only)
Score: 99/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 98, longevity 100
- inputs: {"age_days": 3288, "days_push": 7, "days_rel": 12, "gap_med": 26.0, "n_releases_24m": 27}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 4092, forks 359 (observed 2026-08-28T04:08:34.633712+00:00)

## What it is
NullAway is an Error Prone plugin that performs fast, annotation-based nullability checking for Java code to eliminate NullPointerExceptions. It runs on every build with under 10% overhead, catching most production NPEs with a reasonable annotation burden.

## Use cases
- eliminate NullPointerExceptions in Java code
- add null safety checks to a Gradle build
- find potential null dereferences before runtime
- enforce @Nullable annotations across a Java codebase
- add nullability checking to an Android app
- run fast static analysis on every build

## When to choose
- you want fast null checking that can run on every build
- you prefer annotation-based nullability similar to Kotlin or Swift
- you already use Error Prone or Gradle
- you want a practical balance of safety versus annotation burden

## When to avoid
- you need exhaustive formal verification of all possible NPEs
- your project cannot use JDK 17+ or Error Prone
- you cannot add nullability annotations to your codebase

## Facets
- artifact type: library
- maturity: active
- function: linter, developer-tools, build-tool
- domain: developer-tools, programming-languages, android-tools
- platform: jvm, cli
- tags: null-safety, error-prone-plugin, nullpointerexception, static-code-analysis, jspecify, android

## Member repositories
- uber/NullAway (main) score 99

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:34.633712+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 2026-08-29T18:23:20.938800+00:00, confidence not recorded.
  - readme: https://github.com/uber/NullAway (fetched 2026-08-28T04:08:34.633712+00:00, sha f6da7eb6c1a5)
- Data as of 2026-08-30T08:39:29.467469+00:00.