The End of Silent Localization Errors in .NET Apps - Meet resx-lint

resx-lint is a .NET global tool that validates .resx localization keys against your XAML and C# source files. It catches missing keys before they reach production, auto-fixes common problems, and integrates directly into your build pipeline so errors appear inline in Visual Studio, Rider, and any CI output.

https://github.com/CW-Software-Apps/resx-lint

Features

• Static analysis — scans {maui:Translate Key} in XAML and AppResources.Key in C# and reports missing keys as build errors
• Auto-fixes — removes duplicate keys, adds missing Designer.cs properties, and backfills orphaned language entries automatically
• MSBuild-native errors — emits file(line): error TRANS001: ... format so VS/Rider show inline squiggles with clickable links
• Similar key suggestions — when a key is missing, suggests the closest matches to help spot typos quickly
• --what-if mode — preview every change without touching any file
• CI-friendly — --fail-on-warnings escalates warnings to errors for stricter pipelines
• Zero dependencies — single self-contained executable, no extra NuGet packages required

Installation

Global (local dev)

dotnet tool install --global ResxLint

Per-repo (recommended for teams and CI)

dotnet new tool-manifest        # creates .config/dotnet-tools.json — commit this file
dotnet tool install ResxLint

New devs and CI agents just run once:

dotnet tool restore

Usage

resx-lint --project-dir <dir> --resx-file <path> [options]

MSBuild Integration

Drop this target into your .csproj to validate on every build.

The snippet below checks whether resx-lint is installed before running it and emits a clear, actionable error message if it is not — instead of the cryptic exited with code 9009 you'd get otherwise:

<Target Name="ValidateTranslationKeys" BeforeTargets="BeforeBuild">

  <!-- Friendly error if resx-lint is not installed -->
  <Exec Command="resx-lint --help"
        ConsoleToMSBuild="true"
        IgnoreExitCode="true"
        StandardOutputImportance="low"
        StandardErrorImportance="low">
    <Output TaskParameter="ExitCode" PropertyName="_ResxLintExitCode" />
  </Exec>
  <Error
    Condition="'$(_ResxLintExitCode)' == '9009' OR '$(_ResxLintExitCode)' == '127'"
    Text="resx-lint is not installed. Run: dotnet tool install --global ResxLint   |   Docs: https://github.com/CW-Software-Apps/resx-lint" />

  <!-- Run validation -->
  <Exec
    Command="resx-lint --project-dir &quot;$(MSBuildProjectDirectory)&quot; --resx-file &quot;$(MSBuildProjectDirectory)\Resources\AppResources.resx&quot;"
    ConsoleToMSBuild="true"
    IgnoreExitCode="false" />

</Target>

If the tool is missing, the build stops with:

error : resx-lint is not installed. Run: dotnet tool install --global ResxLint
        Docs: https://github.com/CW-Software-Apps/resx-lint

For strict mode (warnings become errors), add --fail-on-warnings to the Exec command.

CI/CD Integration

GitHub Actions

- name: Setup .NET
  uses: actions/setup-dotnet@v4
  with:
    dotnet-version: '10.x'

- name: Restore tools
  run: dotnet tool restore        # reads .config/dotnet-tools.json

- name: Validate translations
  run: resx-lint --project-dir . --resx-file Resources/AppResources.resx --fail-on-warnings

Docker / Coolify / Self-hosted

If your CI/CD builds via Docker (e.g. Coolify on Hostinger), install the tool in your Dockerfile and run it before dotnet publish:

# Install resx-lint
RUN dotnet tool install --global ResxLint
ENV PATH="${PATH}:/root/.dotnet/tools"

# Copy sources
COPY [".", "/src/app"]

# ✅ Validate translations — fails the Docker build if keys are missing
RUN resx-lint \
    --project-dir /src/app \
    --resx-file /src/YourLibrary/Resources/AppResources.resx

# Build
RUN dotnet publish MyApp.csproj -f net10.0-android -c Release

The tool exits with code 3 on fatal errors, which causes the Docker build to fail and stops the Coolify deployment before a broken build reaches production.

Diagnostic Codes

Fatal errors (TRANS001, TRANS004) stop the build immediately. Auto-fixes (TRANS002, TRANS003, TRANS005) modify files and return exit code 1 so MSBuild restarts the build to re-validate.

Exit Codes

Output Sample

═══ 4/6 Validating XAML usage ({maui:Translate}) ═══

Views/HomePage.xaml(42) : error TRANS001 : Translation key 'WelcomeTitel' not found in AppResources.resx. Similar keys: 'WelcomeTitle'.

────────────────────────────────────────────────────────────
 SUMMARY — resx-lint
────────────────────────────────────────────────────────────
  .resx base          : Resources\AppResources.resx
  Keys in base        : 312
  Languages           : 2  (AppResources.en-US.resx, AppResources.es-ES.resx)
  Auto-fixes applied  : 0
  Warnings            : 0
  Fatal errors        : 1
────────────────────────────────────────────────────────────

  ✖ Build cancelled: 1 fatal error(s). Fix the missing keys and rebuild.

Requirements

• .NET 10 SDK or later

License

MIT © CW Software