I built a CLI tool that explains Java stack traces and suggests fixes

Abenezer Anglo — Mon, 13 Apr 2026 20:46:22 +0000

Tired of Googling the same Java errors over and over?

I built StackLens, a CLI tool that analyzes your logs or stack traces and tells you what went wrong and how to fix it.

How it works

java -jar stacklens.jar analyze --text "java.lang.NullPointerException at UserService.java:42"

Output:

Issue: NullPointerException
Severity: HIGH
Explanation: A method was called on a null object reference at UserService.java:42
Suggested Fix: Add null checks before accessing the object, or use Optional<T>

You can also analyze a full log file:

java -jar stacklens.jar analyze --file app.log

Or get JSON output to pipe into other tools:

java -jar stacklens.jar analyze --file app.log --format json

What it detects

NullPointerException
OutOfMemoryError
Connection refused
Database connection failures
HTTP 500 errors
Thread pool exhaustion
Timeouts
Authentication errors

No Maven required

Linux/macOS:

curl -L https://github.com/AbaSheger/stacklens/releases/latest/download/stacklens.jar -o stacklens.jar
java -jar stacklens.jar analyze --text "your stack trace here"

Windows (PowerShell):

Invoke-WebRequest -Uri "https://github.com/AbaSheger/stacklens/releases/latest/download/stacklens.jar" -OutFile "stacklens.jar"
java -jar stacklens.jar analyze --text "your stack trace here"

Built with Java 17 + picocli. 51 unit tests. Open source.

GitHub: https://github.com/AbaSheger/stacklens

Would love feedback — especially on error types you'd want added.

DEV Community: Abenezer Anglo

I built a CLI tool that explains Java stack traces and suggests fixes

How it works

What it detects

No Maven required