A Windows desktop diff tool for comparing git branches, with AI-powered code review and explanation.
Built on .NET MAUI + Blazor Hybrid targeting net10.0-windows10.0.19041.0.
- Compare any two branches (or pinned commits) in a local git repository
- Syntax-highlighted unified diff with collapsible file sections
- AI review and explanation via Claude (Claude Code CLI), GitHub Copilot, or Ollama (self-hosted)
- Analysis link navigation — AI references to
File.cs:42are clickable and scroll the diff to that line - Severity-aware analysis indicators — findings are tagged critical/high/medium/low and displayed with matching intensity
- Configurable diff context depth (3 / 10 / 25 / 50 lines per hunk) for richer AI context
- Markdown export of the full diff
- Per-repo branch selection memory, light/dark theme, font ligature toggle
- Windows 10 (19041+) or Windows 11
- .NET 10 SDK with MAUI workload
giton PATH- For Claude: Claude Code CLI authenticated (
claude auth login) - For GitHub Copilot: a GitHub account with Copilot access (sign-in handled in-app)
- For Ollama: a running Ollama instance (default
http://localhost:11434); configure endpoints in Settings
Search for DiffThis in the Microsoft Store, or install directly:
Click Open Repository and select any local git repo folder. Recently opened repos appear on the home screen for quick access.
Pick a Base and Compare branch from the dropdowns. Optionally check Specific Commit on either side to pin the diff to a particular commit. Click Compare →.
The Diff tab shows a file sidebar with add/remove counts and a syntax-highlighted unified diff. Click any file in the sidebar to jump to it. Use the context-lines control (top right) to show more surrounding code.
Switch to the Analysis tab. Select a model from the Context or Code Review dropdowns and click + to generate a result. Results are cached — re-opening the same diff is instant.
AI findings that reference specific files (e.g. Services/GitService.cs:42) are rendered as clickable links that scroll the diff to that exact line.
Open Settings (gear icon, top right) to sign in to Claude or GitHub Copilot, or add an Ollama endpoint. Once connected, available models are fetched automatically.
- Claude — requires Claude Code CLI installed and authenticated (
claude auth loginin a terminal) - GitHub Copilot — sign in with your GitHub account directly from the Settings page
- Ollama — add a base URL (e.g.
http://localhost:11434) for any running Ollama instance
# Debug
dotnet build DiffThis\DiffThis.csproj -f net10.0-windows10.0.19041.0
# Release
dotnet build DiffThis\DiffThis.csproj -f net10.0-windows10.0.19041.0 -c Release
# Run
dotnet run --project DiffThis\DiffThis.csproj -f net10.0-windows10.0.19041.0
# Tests
dotnet test DiffThis.AI.OpenAI.Tests\DiffThis.AI.OpenAI.Tests.csprojThe target framework must always be specified explicitly for the MAUI project. In debug builds, Blazor DevTools are accessible via F12.
DiffThis/ MAUI app host (entry point)
DiffThis.UI/ Razor components, pages, panels
DiffThis.Core/ Domain models (DiffResult, DiffFile, DiffHunk, DiffLine)
DiffThis.AI.Shared/ PromptService, AiCacheService, AnalysisLinkService, DiffSessionService
DiffThis.AI.Claude/ Claude CLI integration
DiffThis.AI.OpenAI/ GitHub Copilot + Ollama integration (OpenAI-compatible API)
DiffThis.AI.OpenAI.Tests/ Integration tests for Copilot services
Key files:
DiffThis/
├── MauiProgram.cs DI registration; DevTools in debug
└── MainPage.xaml Hosts the BlazorWebView
DiffThis.UI/Components/Pages/
├── Home.razor Repo folder picker
├── BranchSelection.razor Branch + commit-pin pickers; triggers diff
├── MainView.razor Side-by-side / tabbed layout for diff + analysis
└── Settings.razor App settings
DiffThis.UI/Components/Panels/
├── DiffPanel.razor File sidebar + collapsible diff tables + syntax highlighting
└── AnalysisPanel.razor AI result cards; analysis link rendering
DiffThis.UI/wwwroot/
├── app.css CSS variables for syntax token colours (light/dark)
└── app.js JS interop: scrollToElement, copyToClipboard, analysis link callback
Uses the claude CLI as a subprocess (diff passed on stdin). Requires Claude Code to be installed and authenticated via claude auth login. Model list is fetched from the Anthropic API using your CLI credentials.
Calls the GitHub Copilot chat completions API directly. Sign in with your GitHub account from the Settings page — DiffThis handles the device-code OAuth flow and session token refresh automatically. Requires a GitHub account with Copilot access.
Calls a local (or remote) Ollama instance via its /api/chat endpoint. Add one or more endpoints in Settings (name, base URL, optional API key, optional per-endpoint timeout). DiffThis fetches available models from each endpoint and lets you pull new models directly from the UI. The context window (num_ctx) is sized automatically based on the prompt length to avoid truncation.
Custom prompt templates can be placed at %LOCALAPPDATA%\DiffThis\prompts\review.md or explain.md. Use {{Variable}} placeholders — the built-in templates in DiffThis.AI.Shared/Prompts/ show available variables.
Available placeholders:
| Placeholder | Value |
|---|---|
{{RepositoryName}} |
Repo folder name |
{{BaseDisplay}} |
Human-readable base ref label |
{{CompareDisplay}} |
Human-readable compare ref label |
{{FileCount}} |
Number of files changed |
{{Additions}} |
Total lines added |
{{Deletions}} |
Total lines deleted |
{{FileList}} |
Changed files with status and detected language |
{{DiffContent}} |
Full unified diff (truncated at 60 k chars) |
The number of context lines shown per hunk (equivalent to git diff --unified=N) is configurable from Settings → Diff → Context lines. Options: 3 (minimal, default), 10 (standard), 25 (extended), 50 (full). More context lines give the AI more surrounding code to reason about, at the cost of longer diffs and higher token usage.
AI results are cached at %LOCALAPPDATA%\DiffThis\ai-cache.json (max 500 entries, LRU-evicted). The cache key includes repo path, base/compare refs, feature, model, tools-enabled flag, and max-turns — changing any of these produces a fresh run.