GitHub - CW-Software-Apps/resx-lint: Complete .resx localization quality tool for .NET - validates keys against XAML and C#, auto-fixes duplicates, AI-powered translation, web UI editor, MSBuild integration.

resx-lint is more than a localization checker — it is a complete .resx quality and productivity tool for .NET apps.

It validates your localization keys against both XAML and C#, catching missing, duplicate, orphaned, and untranslated entries before they reach production. That means fewer runtime surprises, cleaner resource files, and a much more reliable localization workflow.

What makes resx-lint stand out is its AI-powered translation workflow. When keys are missing or placeholders need to be filled, the built-in web UI can automatically translate them using AI providers (OpenAI, Anthropic, Azure, Google, DeepSeek, or custom endpoints), helping you localize entire resource sets in seconds instead of manually editing each string one by one.

Key Benefits

Validates .resx files against real application usage in XAML and C#
Detects missing, duplicate, case-only duplicate, orphaned, and untranslated keys
Suggests likely matches for typos and naming mistakes
add-key/remove-key commands that touch every language file + Designer.cs in one call — see For AI Agents
Offers automatic translation with AI for missing or incomplete entries
Provides a fast, visual web UI editor for reviewing and applying changes
Integrates cleanly with CLI, CI, and MSBuild
Helps teams keep localization consistent across multiple languages and projects
Built for speed and confidence

Whether you are maintaining a single app or a large multilingual product, resx-lint helps you keep translation files clean, accurate, and up to date. You can audit, fix, preview, and translate from one place — with AI doing the heavy lifting when you need to move fast.

Features

🔍 CLI Linter

Static analysis — scans {maui:Translate Key} in XAML and AppResources.Key in C#
Auto-fixes — removes duplicate keys, adds missing Designer.cs properties, backfills orphaned language entries
Case-only duplicate detection — catches TipoDeServico vs TipoDeServiCO: two keys that both compile fine but silently render [MISSING: Key] at runtime depending on which casing a binding happens to use (TRANS009)
MSBuild-native errors — emits file(line): error TRANS001: ... for inline squiggles in VS/Rider
Similar key suggestions — suggests closest matches for typos
--what-if mode — preview every change without touching files
CI-friendly — --fail-on-warnings escalates warnings to errors

🤖 `add-key` / `remove-key` — safe key management for AI agents and humans

add-key — adds one key to the base .resx + every language .resx + Designer.cs in a single call; refuses outright if a case-variant of the key already exists instead of silently creating the TRANS009 bug
remove-key — deletes one exact key from every .resx + Designer.cs; optional --project-dir safety check refuses to remove a key still referenced in XAML/C#
Both are idempotent, --what-if-able, and print copy-paste-ready {maui:Translate Key} / AppResources.Key usage — see For AI Agents below

🖥️ Web UI Dashboard

Translation Matrix Editor — edit all language cells side-by-side in a virtual-scrolled grid
🇧🇷 Language flags — locale-to-flag conversion (Regional Indicator Symbols)
Configurable base language — pick your source language (e.g. pt-BR) via searchable picker
Live missing count — header badges update in real time as you type
AI batch translate — translate missing/placeholder keys via OpenAI, Anthropic, Azure, Google, DeepSeek, or custom endpoints
Auto-fix preview & apply — see what changes before writing to disk
Project manager — save multiple projects, scan for .resx files, quick audit
Self-update — one-click dotnet tool update inside the UI
Sound effects — optional audio feedback on save, translate, and errors
Dark/Light theme — persistent toggle
🔢 Keyboard shortcuts — Ctrl+1/2/3 views, Ctrl+Enter audit, Ctrl+S save, Ctrl+F search, Esc close modals
Export/Import Excel — spreadsheet round-trip for translation managers
Virtual scrolling — handles 10,000+ keys without freezing

Screenshots

TODO: Replace these placeholders with actual screenshots.

Projects Dashboard	Translation Matrix

Lint Results	AI Translation Config

Installation

Global (local dev)

dotnet tool install --global ResxLint

Per-repo (recommended for teams and CI)

dotnet new tool-manifest
dotnet tool install ResxLint

New devs and CI agents just run:

dotnet tool restore

Usage

Interactive Mode

resx-lint

Shows a 3-second prompt:

Press W → opens the Web UI at http://localhost:7950
Wait 3s → auto-detects a .resx in the current directory and runs the CLI lint

CLI Lint

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

Option	Description
`--project-dir <dir>`	Root of the project (where `.xaml` and `.cs` files live)
`--resx-file <path>`	Path to the base `.resx` file
`--what-if`	Preview all changes without writing any files
`--fail-on-warnings`	Treat TRANS006 and TRANS007 as fatal errors
`--quiet`	Suppress ✅ OK and ℹ INFO messages
`--help`	Show help and exit

Web UI

resx-lint --serve

Or press W in interactive mode. Opens at http://localhost:7950.

Option	Description
`--port <port>`	Custom port (default: 7950)
`--no-open`	Don't open browser automatically

Update Check

resx-lint --check-update

Or click the version badge in the Web UI header.

`add-key` — add one translation key, safely

resx-lint add-key <Key> --resx-file <path> --value "<base text>" [options]

Option	Description
`--lang <code>=<text>`	Translation for one language file, repeatable (e.g. `--lang en-US="Service Type"`). Any sibling language file not covered gets a `[TRANSLATE: <base text>]` placeholder — never silently left out.
`--update`	Allow changing the value of a key that already exists under the exact same casing. Does not bypass the case-collision refusal below.
`--what-if`	Preview only — report what would change, write nothing.

Refuses outright if a case-variant of the key already exists (e.g. you ask for tipoDeServico and TipoDeServico is already there) — that's the exact bug TRANS009 exists to catch, and add-key makes it structurally impossible to reintroduce. See For AI Agents for the full rationale and worked examples.

resx-lint add-key TipoDeServico --resx-file Resources/AppResources.resx \
  --value "Tipo de Serviço" \
  --lang en-US="Service Type" --lang es-ES="Tipo de Servicio"

`remove-key` — delete one key everywhere

resx-lint remove-key <Key> --resx-file <path> [options]

Option	Description
`--project-dir <dir>`	If given, refuses to remove a key still referenced in any `.xaml`/`.cs` under this directory. Omit to skip the check.
`--force`	Remove even if `--project-dir` found live references.
`--what-if`	Preview only.

Case-insensitive as a lookup convenience only — if more than one case-variant exists (e.g. both OK and Ok), it refuses and lists them so you state the exact one to delete; it never guesses between two coexisting keys.

resx-lint remove-key TipoDeServiCO --resx-file Resources/AppResources.resx --project-dir .

MSBuild Integration

Add this target to your .csproj to run validation on every build:

<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>

Linux / CI / Docker: Always use forward slashes in the --resx-file path. $(MSBuildProjectDirectory)/Resources/AppResources.resx works on both Windows and Linux.

If the tool is not installed, the build stops with a clear message instead of the cryptic exited with code 9009.

For strict mode, add --fail-on-warnings to the Exec command.

CI/CD Integration

GitHub Actions

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

Docker / Coolify

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

COPY [".", "/src/app"]
RUN resx-lint --project-dir /src/app --resx-file /src/YourLibrary/Resources/AppResources.resx

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

Exit code 3 on fatal errors stops the Docker build, preventing broken deployments.

Diagnostic Codes

Code	Severity	Description	Action
`TRANS001`	❌ Fatal	Key used in `{maui:Translate Key}` (XAML) not found in base `.resx`	Fix manually
`TRANS002`	🔧 Auto-fix	Duplicate key found in a `.resx` file	Extra occurrences removed
`TRANS003`	🔧 Auto-fix	Key in base `.resx` has no corresponding property in `Designer.cs`	Property added automatically
`TRANS004`	❌ Fatal	Key accessed as `AppResources.Key` (C#) not found in base `.resx`	Fix manually
`TRANS005`	🔧 Auto-fix	Key exists in a language file but not in the base `.resx`	Added to base with `[TRANSLATE]` placeholder
`TRANS006`	⚠️ Warning	Key in base `.resx` has no translation in one or more language files	Add translation or escalate with `--fail-on-warnings`
`TRANS007`	⚠️ Warning	Base `.resx` value is empty or a placeholder like `[TRANSLATE]`	Translation pending
`TRANS009`	🔧 Auto-fix / ⚠️/❌	Two keys in the base `.resx` differ only in casing (e.g. `TipoDeServico` vs `TipoDeServiCO`) — both compile fine as separate `Designer.cs` properties, so this silently ships `[MISSING: Key]` at runtime depending on which casing a binding happens to use	If exactly one variant is referenced anywhere: the unreferenced one is removed automatically. If neither is referenced: flagged as a warning, pick one to keep with `remove-key`. If both are referenced somewhere: flagged fatal — merge those usages onto one key first, resx-lint won't guess.

Fatal errors (TRANS001, TRANS004, and an unresolved TRANS009 where both variants are in active use) stop the build immediately. Auto-fixes (TRANS002, TRANS003, TRANS005, and the unambiguous case of TRANS009) modify files and return exit code 1 so MSBuild restarts the build to re-validate.

For AI Agents

If you're an AI coding agent reading this because you're about to edit a .resx file: don't hand-edit it. Use add-key / remove-key instead. This section exists because that exact mistake is what TRANS009 and these two commands were built to stop.

Why hand-editing `.resx` files goes wrong

Every one of these compiles fine, passes code review, and only breaks at runtime as an unhelpful [MISSING: Key] on screen:

Case-variant duplication — you search the base .resx for TipoDeServico, don't find it (because it's actually there as TipoDeServiCO, or it's buried in a 5,000-line file), and add a new <data name="TipoDeServico">. Now two keys exist. System.Resources.ResourceManager is case-sensitive, so whichever casing your new XAML binding or AppResources.X call uses is the only one that resolves — the other sits there dead, or worse, is the one some other part of the app was already using.
Forgetting a language file — you add the key to the base .resx (the default/neutral culture) but forget AppResources.en-US.resx or AppResources.es-ES.resx. Nothing fails locally if your test device is on the default culture; it ships broken for every other language.
Forgetting the Designer.cs property — if the project's build doesn't run resx-lint as a pre-build step, AppResources.Key (C# access) won't compile at all until someone notices and adds the property by hand.

add-key makes all three structurally impossible in one call: it checks for a case-insensitive collision before writing anything (refuses instead of duplicating), writes the base .resx + every sibling language file it finds (backfilling untranslated ones with a [TRANSLATE: ...] placeholder instead of skipping them), and always appends the Designer.cs property.

The workflow

Check first, always (costs nothing, writes nothing):
```
resx-lint add-key MyNewKey --resx-file Resources/AppResources.resx --value "placeholder" --what-if
```
If it refuses with a case-collision error, it just told you the exact existing key to reuse instead — use that, don't add anything.
Add for real, with as many language values as you already know:
```
resx-lint add-key MyNewKey --resx-file Resources/AppResources.resx \
  --value "Texto em português" \
  --lang en-US="English text" --lang es-ES="Texto en español"
```
It's fine to omit --lang entirely — every language file still gets the key, just with a [TRANSLATE: ...] placeholder that a later lint pass (TRANS007) will flag for follow-up, instead of the key being silently absent.
Use the exact key it echoes back in your XAML/C# edit — the command's last lines are always the copy-paste-ready usage:
```
Use it as:
  XAML: {maui:Translate MyNewKey}
  C#:   AppResources.MyNewKey
```
Don't retype the key name from memory into the XAML/C# file; copy it from this output. A single mistyped letter is exactly how a new case-variant duplicate gets created.
Cleaning up a mistake (e.g. you find you did create a near-duplicate before reading this): remove-key deletes one exact key everywhere in one call.
```
resx-lint remove-key MyNewKey --resx-file Resources/AppResources.resx --project-dir .
```
The --project-dir flag makes it refuse if that key is actually still referenced somewhere — you'd otherwise be creating a fresh TRANS001/TRANS004/[MISSING: Key] by deleting something in use.
Before finishing your change, run a full lint pass so anything these two commands didn't cover (existing TRANS001/TRANS004/TRANS006 issues unrelated to your edit) is visible:
```
resx-lint --project-dir . --resx-file Resources/AppResources.resx --what-if
```

Never do this instead

Don't Edit/Write a <data name="..."> block into a .resx XML file directly, "just this once," because it seems faster than shelling out to a CLI tool. It is faster right up until it silently duplicates a key with different casing, or you forget one of three-plus language files — both are invisible until a user reports [MISSING: Key] weeks later.
Don't guess a key's exact casing from memory when referencing it in XAML/C#. If you didn't just create it with add-key (which echoes the exact string), grep the base .resx for it, or run add-key <guess> --what-if and read the refusal message — it names the real key.
Don't resolve a TRANS009 finding by deleting whichever variant "looks newer" without checking usage first. remove-key --project-dir does that check for you; a coin-flip deletion is how a working binding gets broken.

Exit Codes

Code	Meaning
`0`	All OK — no issues found
`1`	Auto-fixes were applied — restart the build to re-validate
`2`	Invalid parameters, or `add-key`/`remove-key` refused (collision, not found, still in use)
`3`	Fatal errors found (TRANS001, TRANS004, or an unresolved TRANS009 case-collision)

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

Name		Name	Last commit message	Last commit date
.github/workflows		.github/workflows
.impeccable		.impeccable
screenshots		screenshots
src/ResxLint		src/ResxLint
.gitignore		.gitignore
CLAUDE.md		CLAUDE.md
DESIGN.md		DESIGN.md
PRODUCT.md		PRODUCT.md
README.md		README.md
banner.png		banner.png
icon.png		icon.png
providers.json		providers.json
resx-lint.slnx		resx-lint.slnx

Navigation Menu

Repository navigation

About

Repository files navigation

Key Benefits

Features

🔍 CLI Linter

🤖 `add-key` / `remove-key` — safe key management for AI agents and humans

🖥️ Web UI Dashboard

Screenshots

Installation

Global (local dev)

Per-repo (recommended for teams and CI)

Usage

Interactive Mode

CLI Lint

Web UI

Update Check

`add-key` — add one translation key, safely

`remove-key` — delete one key everywhere

MSBuild Integration

CI/CD Integration

GitHub Actions

Docker / Coolify

Diagnostic Codes

For AI Agents

Why hand-editing `.resx` files goes wrong

The workflow

Never do this instead

Exit Codes

Output Sample

Requirements

License

About

Releases

Packages

Contributors

Languages

Latest commit

History

Folders and files

Repository files navigation

Key Benefits

Features

🔍 CLI Linter

🤖 add-key / remove-key — safe key management for AI agents and humans

🖥️ Web UI Dashboard

Screenshots

Installation

Global (local dev)

Per-repo (recommended for teams and CI)

Usage

Interactive Mode

CLI Lint

Web UI

Update Check

add-key — add one translation key, safely

remove-key — delete one key everywhere

MSBuild Integration

CI/CD Integration

GitHub Actions

Docker / Coolify

Diagnostic Codes

For AI Agents

Why hand-editing .resx files goes wrong

The workflow

Never do this instead

Exit Codes

Output Sample

Requirements

License

About

Resources

Stars

Watchers

Forks

Releases

Packages

Contributors

Languages

🤖 `add-key` / `remove-key` — safe key management for AI agents and humans

`add-key` — add one translation key, safely

`remove-key` — delete one key everywhere

Why hand-editing `.resx` files goes wrong