errex 0.9.0

Paste or pipe any error message and get a plain-English explanation powered by Claude

errex — Error Explainer

Paste or pipe any error message and get a clear, plain-English explanation powered by Claude.

$ cat traceback.txt | errex

────────────────────── errex — Error Analysis ──────────────────────

**TypeError: unsupported operand type(s) for +: 'int' and 'str'**

This is a Python type error. You're trying to add an integer and a
string together, which Python doesn't allow...

Install

pip install errex
export ANTHROPIC_API_KEY=sk-ant-...

Requires Python 3.9+ and an Anthropic API key.

Quick start

errex                        # interactive paste
errex traceback.txt          # read from a file
cat error.log | errex        # pipe from stdin
errex --watch server.log     # tail a log, auto-explain errors

All flags

Explaining errors

Flag	What it does
errex [FILE]	Explain an error from a file, stdin, or interactive paste
--brief	One-paragraph summary instead of full analysis
--fix	Output only the fix command, no explanation
--lang LANG	Language hint when the error is ambiguous (e.g. rust, go, java)
--model MODEL	Choose which Claude model to use (default: claude-sonnet-4-6)
--json	Structured JSON output: error_type, root_cause, fix_steps, gotchas
--context FILE	Attach a source file as extra context for more targeted explanations
errex A.txt B.txt	Compare two error files and find shared root causes

Code tools

Flag	What it does
--explain-code FILE	Walk through what a piece of code does in plain English
--lint FILE	Scan a code file for bugs, security issues, and anti-patterns
--test-gen FILE	Generate a test case for a code file; pipe an error to reproduce the bug
--explain-diff [FILE]	Explain a git diff — pipe git diff | errex --explain-diff or pass a .patch file

History & search

Flag	What it does
--history [SEARCH]	View past explanations, optionally filtered by keyword
--recent [N]	Show the last N explanations (default: 5)
--similar	Find past errors in your history that match the current one
--ask "question"	Ask a follow-up about the last error without re-explaining it
--retry	Re-explain the last error with different flags (e.g. --retry --model claude-opus-4-7)
--stats	Usage dashboard: total runs, models, top error types, busiest day/hour
--export FILE	Export history to a styled HTML or Markdown file (--export-format html|md)
--clear-history [DAYS]	Delete all history, or only entries older than N days

Workflow

Flag	What it does
--watch LOGFILE	Tail a log file and auto-explain new errors (deduplicates repeats)
--summarize-log FILE	Digest all distinct error types in a large log file
--issues	Search GitHub Issues for bugs matching your error
--share	Post the explanation to paste.rs and print a shareable link
--copy	Copy the explanation to the clipboard
--chat	Stay in a Q&A loop after the explanation
--notify	Send a desktop notification when the explanation is ready

Setup & config

Flag	What it does
--config [key=value]	View or edit ~/.errexrc — e.g. --config model=claude-opus-4-7
--setup	First-run wizard: check API key, detect languages, write config, install shell integration
--scan	Scan common log locations for recent error files and pick one to explain
--install-shell	Add errex-last() to your shell — run it after any failed command
--web	Launch a local web UI at http://localhost:7337
--tokens	Show input/output token counts after each explanation
--update	Check PyPI for a newer version
--version	Show the installed version

Config file

~/.errexrc sets your defaults (all fields optional):

{
  "model": "claude-opus-4-7",
  "brief": false,
  "lang": "python",
  "copy": false
}

Or manage it from the CLI:

errex --config                        # show all settings
errex --config model=claude-opus-4-7  # set a value
errex --config lang=null              # reset to default

Shell integration

errex --install-shell   # adds errex-last() to ~/.zshrc or ~/.bashrc

After any failed command, run errex-last to explain why it failed.

History

Every explanation is saved to ~/.errex_history (one JSON object per line).

errex --recent           # last 5 explanations
errex --history KeyError # search history
errex --stats            # usage dashboard
errex --export report.html  # export to HTML

What you get

For any error, errex explains:

1. What kind of error it is and which language or tool produced it
2. What it means in plain English
3. The most likely root cause, ranked by probability
4. Numbered fix steps with code snippets where helpful
5. Common gotchas — the non-obvious things that trip people up