diff --git a/src/core/core-definitions.ts b/src/core/core-definitions.ts
index 43cc56e..9664920 100644
--- a/src/core/core-definitions.ts
+++ b/src/core/core-definitions.ts
@@ -1,5 +1,6 @@
 import { TServiceType } from "../services/service-definitions";
 import { TMatcherType } from "../matchers/matcher-definitions";
+import { TMiddlewareType } from "../middleware/middleware-definitions";
 
 export type TSet = Map<string, string | null>;
 
@@ -12,6 +13,7 @@ export interface CoreArgs {
   serviceConfig: string | null;
   matcher: TMatcherType;
   prompt: string;
+  middleware: TMiddlewareType[]
 }
 
 export interface TChangeSet {
@@ -42,4 +44,5 @@ export interface CliArgs extends Record<string, string | undefined> {
   service: string;
   serviceConfig?: string;
   matcher: string;
+  middleware?: string
 }
diff --git a/src/core/invoke-translation-service.ts b/src/core/invoke-translation-service.ts
index 4997375..f000360 100644
--- a/src/core/invoke-translation-service.ts
+++ b/src/core/invoke-translation-service.ts
@@ -11,6 +11,9 @@ import {
   TServiceArgs,
   TString,
 } from "../services/service-definitions";
+import {
+  instantiateTMiddleware
+} from "../middleware/middleware-definitions";
 
 export async function invokeTranslationService(
   serviceInputs: TSet,
@@ -84,7 +87,8 @@ async function runTranslationService(
     `Invoke '${args.service}' from '${args.srcLng}' to '${args.targetLng}' with ${serviceArgs.strings.length} inputs...`
   );
   const translationService = await instantiateTService(args.service);
-  const rawResults = await translationService.translateStrings(serviceArgs);
+  const translationMiddleware = await instantiateTMiddleware(args.middleware, translationService)
+  const rawResults = await translationMiddleware.processTranslation(serviceArgs);
   return rawResults.map((rawResult) => {
     const cleanResult = reInsertInterpolations(
       rawResult.translated,
diff --git a/src/core/translate-cli.ts b/src/core/translate-cli.ts
index a339632..a81d340 100644
--- a/src/core/translate-cli.ts
+++ b/src/core/translate-cli.ts
@@ -11,6 +11,7 @@ import {
 } from "../file-formats/file-format-definitions";
 import { getTServiceList, TServiceType } from "../services/service-definitions";
 import { getTMatcherList, TMatcherType } from "../matchers/matcher-definitions";
+import { TMiddlewareType } from "../middleware/middleware-definitions";
 
 async function resolveOldTarget(
   args: CliArgs,
@@ -98,6 +99,9 @@ export async function translateCli(cliArgs: CliArgs) {
     serviceConfig: cliArgs.serviceConfig ?? null,
     matcher: cliArgs.matcher as TMatcherType,
     prompt: cliArgs.prompt ?? "",
+    middleware: (cliArgs.middleware ?? "")
+        .split(",")
+        .filter((s) => s) as TMiddlewareType[]
   };
   const result = await translateCore(coreArgs);
 
diff --git a/src/index.ts b/src/index.ts
index 3219b69..67f4347 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -6,6 +6,7 @@ import { getTFileFormatList } from "./file-formats/file-format-definitions";
 import { getTMatcherList } from "./matchers/matcher-definitions";
 import { getTServiceList } from "./services/service-definitions";
 import { extractVersion } from "./util/extract-version";
+import { getTMiddlewareList } from "./middleware/middleware-definitions";
 
 process.on("unhandledRejection", (error) => {
   console.error("[fatal]", error);
@@ -15,6 +16,10 @@ function formatOneOfOptions(options: string[]): string {
   return `One of ${formatCliOptions(options)}`;
 }
 
+function formatManyOfOptions(options: string[]): string {
+  return `Comma-separated list of ${formatCliOptions(options)}`
+}
+
 export function run(process: NodeJS.Process, cliBinDir: string): void {
   commander.storeOptionsAsProperties(false);
   commander.addHelpCommand(false);
@@ -60,6 +65,10 @@ export function run(process: NodeJS.Process, cliBinDir: string): void {
       "--prompt <prompt>",
       "supply a prompt for the AI translation service"
     )
+    .option(
+      "--middleware <middleware>",
+      formatManyOfOptions(getTMiddlewareList())
+    )
     .version(extractVersion({ cliBinDir }), "-v, --version")
     .parse(process.argv);
 
@@ -79,6 +88,7 @@ export function run(process: NodeJS.Process, cliBinDir: string): void {
     serviceConfig: commander.opts().serviceConfig,
     matcher: commander.opts().matcher,
     prompt: commander.opts().prompt,
+    middleware: commander.opts().middleware,
   };
   translateCli(args)
     .then(() => {
diff --git a/src/middleware/middleware-definitions.ts b/src/middleware/middleware-definitions.ts
new file mode 100644
index 0000000..e8532a2
--- /dev/null
+++ b/src/middleware/middleware-definitions.ts
@@ -0,0 +1,38 @@
+import { TServiceArgs, TResult, TService } from '../services/service-definitions'
+
+export interface TMiddleware {
+  next?: TMiddleware
+  processTranslation(args: TServiceArgs): Promise<TResult[]>
+}
+
+const middlewareMap = {
+  'sanitize-key': null,
+};
+
+export type TMiddlewareType = keyof typeof middlewareMap;
+
+export function getTMiddlewareList(): TMiddlewareType[] {
+  return Object.keys(middlewareMap) as TMiddlewareType[];
+}
+
+export async function instantiateTMiddleware(
+  middlewares: TMiddlewareType[],
+  service: TService,
+): Promise<TMiddleware> {
+  let next: TMiddleware = {
+    processTranslation(args) {
+        return service.translateStrings(args)
+    },
+  }
+
+  while(middlewares.length > 0) {
+    let middlewareType = middlewares.pop()!
+    switch(middlewareType) {
+      case "sanitize-key":
+        next = new (await import("./sanitize-key")).SanitizeKey(next)
+        break;
+    }
+  }
+
+  return next
+}
\ No newline at end of file
diff --git a/src/middleware/sanitize-key.ts b/src/middleware/sanitize-key.ts
new file mode 100644
index 0000000..ac8fb01
--- /dev/null
+++ b/src/middleware/sanitize-key.ts
@@ -0,0 +1,37 @@
+import { TServiceArgs, TResult } from "../services/service-definitions";
+import { TMiddleware } from "./middleware-definitions";
+
+interface SKey {
+  new: string
+  old: string
+}
+
+export class SanitizeKey implements TMiddleware {
+  next: TMiddleware
+  _sanitizedKeys: SKey[] = []
+
+  constructor(next: TMiddleware) {
+    this.next = next
+  }
+
+  async processTranslation(args: TServiceArgs): Promise<TResult[]> {
+    this._sanitizedKeys = args.strings.map(({key}) => {
+      return {
+        new: key.replace(/[^a-zA-Z0-9_]+/g, '_'),
+        old: key,
+      }
+    })
+    
+    for (let i = 0; i < this._sanitizedKeys.length; i++) {
+      args.strings[i].key = this._sanitizedKeys[i].new
+    }
+
+    const res = await this.next.processTranslation(args)
+
+    for (let i = 0; i < this._sanitizedKeys.length; i++) {
+      res[i].key = this._sanitizedKeys[i].old
+    }
+
+    return res
+  }
+}
\ No newline at end of file
diff --git a/test/core/core-test-util.ts b/test/core/core-test-util.ts
index 2e8e9ed..10b6766 100644
--- a/test/core/core-test-util.ts
+++ b/test/core/core-test-util.ts
@@ -89,6 +89,7 @@ export const commonArgs: Omit<CoreArgs, "oldTarget" | "src"> = {
   srcLng: "en",
   targetLng: "de",
   prompt: "",
+  middleware: [],
 };
 
 export async function translateCoreAssert(