In modern Go projects, it's too easy for accidental API changes or subtle documentation edits to sneak through pull requests or release processes unnoticed. relimpact is a lightweight CLI tool that helps you understand what really changed between two Git refs — with clean, structured, human-friendly reports. relimpact what really changed Use it in CI pipelines, release PRs, or locally before tagging new versions. ✨ Features 🔍 API Diff — Track breaking public API changes (structs, interfaces, functions, constants, variables).
📝 Docs Diff — Section-aware Markdown diff to highlight meaningful content changes.
🗂️ Other Files Diff — Group file changes by extension (.sh, .sql, .json, etc.) to surface migrations and auxiliary files.
🚀 Designed for Release PR reviews — Quickly see the real impact of changes.
🖋️ Markdown Reports — Ready to paste into GitHub Releases, Slack, or changelogs.
⚙️ Works in GitHub Actions, GitLab CI, or locally — Integrates easily.
🔒 No server required — Pure CLI tool. 🔍 API Diff — Track breaking public API changes (structs, interfaces, functions, constants, variables). API Diff 📝 Docs Diff — Section-aware Markdown diff to highlight meaningful content changes. Docs Diff 🗂️ Other Files Diff — Group file changes by extension (.sh, .sql, .json, etc.) to surface migrations and auxiliary files. Other Files Diff 🚀 Designed for Release PR reviews — Quickly see the real impact of changes. Designed for Release PR reviews 🖋️ Markdown Reports — Ready to paste into GitHub Releases, Slack, or changelogs. Markdown Reports ⚙️ Works in GitHub Actions, GitLab CI, or locally — Integrates easily. Works in GitHub Actions, GitLab CI, or locally 🔒 No server required — Pure CLI tool. No server required 🚀 Quickstart Run on a GitHub PR: relimpact --old=v1.0.0 --new=HEAD > release-impact.md relimpact --old=v1.0.0 --new=HEAD > release-impact.md Example Output: ⚙️ GitHub Action Integration name: Release Impact on PR

on:
  pull_request:
    branches: [ master ]
    types: [ opened, synchronize, reopened ]

jobs:
  release-impact:
    name: Generate Release Impact Report
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Determine previous tag
        id: prevtag
        run: |
          git fetch --tags
          TAG_LIST=$(git tag --sort=-version:refname)
          PREV_TAG=$(echo "$TAG_LIST" | head -n2 | tail -n1)
          echo "Previous tag: $PREV_TAG"
          # Fallback to first tag if no previous
          if [ -z "$PREV_TAG" ]; then
            PREV_TAG=$(echo "$TAG_LIST" | head -n1)
            echo "Fallback to first tag: $PREV_TAG"
          fi
          echo "prev_tag=$PREV_TAG" >> $GITHUB_OUTPUT

      - name: Determine new ref
        id: newref
        run: |
          if [ "${{ github.event_name }}" = "pull_request" ]; then
            echo "new_ref=${{ github.event.pull_request.head.sha }}" >> $GITHUB_OUTPUT
          else
            echo "new_ref=HEAD" >> $GITHUB_OUTPUT
          fi

      - uses: hashmap-kz/relimpact-action@main
        with:
          old-ref: ${{ steps.prevtag.outputs.prev_tag }}
          new-ref: ${{ steps.newref.outputs.new_ref }}
          output: release-impact.md

      - name: Upload Release Impact Report
        uses: actions/upload-artifact@v4
        with:
          name: release-impact-${{ github.run_id }}-${{ github.run_attempt }}
          path: release-impact.md name: Release Impact on PR

on:
  pull_request:
    branches: [ master ]
    types: [ opened, synchronize, reopened ]

jobs:
  release-impact:
    name: Generate Release Impact Report
    runs-on: ubuntu-latest

    steps:
      - uses: actions/checkout@v4
        with:
          fetch-depth: 0

      - name: Determine previous tag
        id: prevtag
        run: |
          git fetch --tags
          TAG_LIST=$(git tag --sort=-version:refname)
          PREV_TAG=$(echo "$TAG_LIST" | head -n2 | tail -n1)
          echo "Previous tag: $PREV_TAG"
          # Fallback to first tag if no previous
          if [ -z "$PREV_TAG" ]; then
            PREV_TAG=$(echo "$TAG_LIST" | head -n1)
            echo "Fallback to first tag: $PREV_TAG"
          fi
          echo "prev_tag=$PREV_TAG" >> $GITHUB_OUTPUT

      - name: Determine new ref
        id: newref
        run: |
          if [ "${{ github.event_name }}" = "pull_request" ]; then
            echo "new_ref=${{ github.event.pull_request.head.sha }}" >> $GITHUB_OUTPUT
          else
            echo "new_ref=HEAD" >> $GITHUB_OUTPUT
          fi

      - uses: hashmap-kz/relimpact-action@main
        with:
          old-ref: ${{ steps.prevtag.outputs.prev_tag }}
          new-ref: ${{ steps.newref.outputs.new_ref }}
          output: release-impact.md

      - name: Upload Release Impact Report
        uses: actions/upload-artifact@v4
        with:
          name: release-impact-${{ github.run_id }}-${{ github.run_attempt }}
          path: release-impact.md 📦 Installation Homebrew brew tap hashmap-kz/homebrew-tap
brew install relimpact brew tap hashmap-kz/homebrew-tap
brew install relimpact Manual Download 👉 Download latest release Download latest release Download latest release 🧠 How It Works 1️⃣ Go Source API Changes Uses Go type system & AST parsing:

Detects breaking changes: method signatures, removed fields, new/removed types, etc.
Ignores formatting & comment noise.
Based on golang.org/x/tools/go/packages. Uses Go type system & AST parsing:

Detects breaking changes: method signatures, removed fields, new/removed types, etc.
Ignores formatting & comment noise.
Based on golang.org/x/tools/go/packages. Detects breaking changes: method signatures, removed fields, new/removed types, etc.
Ignores formatting & comment noise.
Based on golang.org/x/tools/go/packages. Detects breaking changes: method signatures, removed fields, new/removed types, etc. Ignores formatting & comment noise. Based on golang.org/x/tools/go/packages. golang.org/x/tools/go/packages 2️⃣ Markdown Docs Changes Section-aware diff of .md files:

Headings added/removed.
Links and images changes.
Section word count diffs.
Based on goldmark parser. Section-aware diff of .md files:

Headings added/removed.
Links and images changes.
Section word count diffs.
Based on goldmark parser. .md Headings added/removed.
Links and images changes.
Section word count diffs.
Based on goldmark parser. Headings added/removed. Links and images changes. Section word count diffs. Based on goldmark parser. goldmark 3️⃣ Other Files Changes Groups changes by file type:

.sql, .sh, .json, .yaml, .conf, etc.
Uses git diff --name-status. Groups changes by file type:

.sql, .sh, .json, .yaml, .conf, etc.
Uses git diff --name-status. .sql, .sh, .json, .yaml, .conf, etc.
Uses git diff --name-status. .sql, .sh, .json, .yaml, .conf, etc. .sql .sh .json .yaml .conf Uses git diff --name-status. git diff --name-status Why Use It? Most release PRs include: ✅ API changes✅ Doc updates✅ Migration scripts✅ Other important config tweaks But raw git diffis noisy and hard to review.relimpact gives you a release-ready summary, focusing on what's important. raw git diff relimpact release-ready summary 📜 License MIT License. See LICENSE. LICENSE LICENSE 👉 Try it today: https://github.com/hashmap-kz/relimpact https://github.com/hashmap-kz/relimpact https://github.com/hashmap-kz/relimpact If you found this useful, leave a ⭐ on GitHub — it helps others discover the project! Happy releasing 🚀

The code in this story is for educational purposes. The readers are solely responsible for whatever they build with it.

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