diff --git a/src/app.ts b/src/app.ts
index e9d1228..11f75e1 100644
--- a/src/app.ts
+++ b/src/app.ts
@@ -15,6 +15,9 @@ import readRouter from '@src/controller/read';
 import path from 'path';
 import logger from '@src/scripts/logger';
 
+// console.log({ "status": 403, "name": "Error", "message": { "errors": [{ "type": "field", "msg": "Invalid value", "path": "user", "location": "query" }, { "type": "field", "msg": "is required", "path": "lat", "location": "query" }]}});
+// console.log(JSON.stringify({ "status": 403, "name": "Error", "message": { "errors": [{ "type": "field", "msg": "Invalid value", "path": "user", "location": "query" }, { "type": "field", "msg": "is required", "path": "lat", "location": "query" }]}}, null, 2));
+
 // configurations
 config(); // dotenv
 
@@ -26,8 +29,15 @@ app.use((req, res, next) => { // monitor eventloop to block requests if busy
   } else { next(); }
 });
 app.use((req, res, next) => { // clean up IPv6 Addresses
-  if (req.ip) { res.locals.ip = req.ip.startsWith('::ffff:') ? req.ip.substring(7) : req.ip; }
-  next();
+  if (req.ip) {
+    res.locals.ip = req.ip.startsWith('::ffff:') ? req.ip.substring(7) : req.ip;
+    next();
+  } else {
+    const message = "No IP provided"
+    logger.error(message);
+    res.status(400).send(message);
+  }
+
 })
 
 // const slowDownLimiter = slowDown({
diff --git a/src/controller/write.ts b/src/controller/write.ts
index dc0658d..47f7d6b 100644
--- a/src/controller/write.ts
+++ b/src/controller/write.ts
@@ -1,19 +1,83 @@
 import express, { Request, Response, NextFunction } from 'express';
 import { entry } from '@src/models/entry';
 import { validationResult } from 'express-validator';
-import { create as createError } from '@src/error'; 
+import { create as createError } from '@src/error';
+import { slowDown, Options as slowDownOptions } from 'express-slow-down';
+import { rateLimit, Options as rateLimiterOptions } from 'express-rate-limit';
+import logger from '@src/scripts/logger';
+
+// TODO clean up after 1 day?
+// TODO move rateLimit to own file
+const ipsThatReachedLimit: RateLimit.obj = {};
+
+const baseOptions: Partial<rateLimiterOptions & slowDownOptions> = {
+  windowMs: 5 * 60 * 1000,
+  //skip: (req, res) => (res.locals.ip == process.env.LOCALHOST)
+}
+
+const baseSlowDown: Partial<slowDownOptions> = {
+  ...baseOptions,
+  delayAfter: 3, // no delay for amount of attempts
+  delayMs: (used: number) => (used - 3) * 125, // Add delay after delayAfter is reached
+}
+
+const baseRateLimit: Partial<rateLimiterOptions> = {
+  ...baseOptions,
+  limit: 10, // Limit each IP per window
+  standardHeaders: true, // Return rate limit info in the `RateLimit-*` headers
+  legacyHeaders: false, // Disable the `X-RateLimit-*` headers
+}
+
+const errorRateLimiter = rateLimit({
+  ...baseRateLimit,
+  message: 'Too many requests with errors',
+  handler: (req: Request, res: Response, next: NextFunction, options: rateLimiterOptions) => {
+    if (!Object.prototype.hasOwnProperty.call(ipsThatReachedLimit, res.locals.ip)) {
+      logger.error(`[RateLimit] for invalid requests reached ${res.locals.ip}, ${req.get('User-Agent')}`);
+      ipsThatReachedLimit[res.locals.ip] = { limitReachedOnError: true };
+    }
+    res.status(options.statusCode).send(options.message);
+  }
+});
+
+// function customRateLimit(req: Request, res: Response, next: NextFunction) {
+//   console.count("customRateLimit");
+//   if (!validationResult(req).isEmpty()) {
+    
+//   } else {
+//     rateLimit({
+//       ...baseRateLimit,
+//       limit: 20,
+//       handler: (req: Request, res: Response, next: NextFunction, options: rateLimiterOptions) => {
+//         if (!Object.prototype.hasOwnProperty.call(ipsThatReachedLimit, res.locals.ip)) {
+//           logger.error(`[RateLimit] for valid requests reached ${res.locals.ip}, ${req.get('User-Agent')}`);
+//           ipsThatReachedLimit[res.locals.ip] = { limitReachedOnError: false };
+//         }
+//         res.status(options.statusCode).send(options.message);
+//       }
+//     })
+//   }
+// }
+
 
 
 // example call: /write?user=xx&lat=00.000&lon=00.000&timestamp=1704063600000&hdop=0.0&altitude=0.000&speed=0.000&heading=000.0
-async function errorChecking (req:Request, res:Response, next:NextFunction) {
+
+function errorChecking(req: Request, res: Response, next: NextFunction) {
   const errors = validationResult(req);
   if (!errors.isEmpty()) {
-    const errorAsJson = { errors: errors.array()};
-    const errorAsString = JSON.stringify(errorAsJson);
-    const hasKeyErrors =  errors.array().some(error => error.msg.includes("Key"));
-   
-    // send forbidden or unprocessable content
-    return createError(res, hasKeyErrors ? 403 : 422, errorAsString, next)
+
+    // if errors happend, then rateLimit to prevent key bruteforcing
+    errorRateLimiter(req, res, () => {
+      const errorAsJson = { errors: errors.array() };
+      const errorAsString = JSON.stringify(errorAsJson);
+      const hasKeyErrors = errors.array().some(error => error.msg.includes("Key"));
+
+      // send forbidden or unprocessable content
+      return createError(res, hasKeyErrors ? 403 : 422, errorAsString, next)
+    });
+
+    return;
   }
 
   if (req.method == "HEAD") {
@@ -21,22 +85,23 @@ async function errorChecking (req:Request, res:Response, next:NextFunction) {
     return;
   }
 
+  next();
+}
+
+async function writeData(req: Request, res: Response, next: NextFunction) {
   // Regular Save logic from here    
   await entry.create(req, res, next);
 
-  if (!res.locals.error) { 
+  if (!res.locals.error) {
     res.send(req.query);
-  } else { 
-    /* at this point error handling already happend,
-    *  or the request has already been send
-    *  therefor there is no need for it again (only middleware to follow at this point) */
+  } else {
     next();
   }
 }
 
 
 const router = express.Router();
-router.get('/', entry.validate, errorChecking);
-router.head('/', entry.validate, errorChecking);
+router.get('/', slowDown(baseSlowDown), entry.validate, errorChecking, writeData);
+router.head('/', slowDown(baseSlowDown), entry.validate, errorChecking);
 
 export default router;
\ No newline at end of file
diff --git a/types.d.ts b/types.d.ts
index 7cb4c68..064db1f 100644
--- a/types.d.ts
+++ b/types.d.ts
@@ -1,6 +1,14 @@
 
 /* eslint-disable @typescript-eslint/no-unused-vars */
 
+namespace RateLimit {
+	interface obj {
+		[key: string]: {
+			limitReachedOnError: boolean
+		}
+	}
+}
+
 namespace Response {
 	interface Message {
 		message: string;