diff --git a/src/backend/compare/compare.ts b/src/backend/compare/compare.ts
index db4f23fa..4b82e24b 100644
--- a/src/backend/compare/compare.ts
+++ b/src/backend/compare/compare.ts
@@ -14,23 +14,28 @@ import { respondProjectNotFound } from '../common/standard-responses.js';
 import { refreshSecret } from '../util.js';
 import { deleteReport, renderCompare } from './report.js';
 import type { TimelineRequest } from '../../shared/api.js';
+import { getNumberOrError } from '../request-check.js';
+import { log } from '../logging.js';
 
 export async function getProfileAsJson(
   ctx: ParameterizedContext,
   db: Database
 ): Promise<void> {
+  ctx.type = 'application/json';
+
+  const runId = getNumberOrError(ctx, 'runId');
+  if (runId === null) {
+    log.error((ctx.body as any).error);
+    return;
+  }
+
   const start = startRequest();
 
-  ctx.body = await getProfile(
-    Number(ctx.params.runId),
-    ctx.params.commitId,
-    db
-  );
+  ctx.body = await getProfile(runId, ctx.params.commitId, db);
   if (ctx.body === undefined) {
     ctx.status = 404;
     ctx.body = {};
   }
-  ctx.type = 'application/json';
   completeRequestAndHandlePromise(start, db, 'get-profiles');
 }
 
@@ -70,17 +75,24 @@ export async function getMeasurementsAsJson(
   ctx: ParameterizedContext,
   db: Database
 ): Promise<void> {
+  ctx.type = 'application/json';
+
+  const runId = getNumberOrError(ctx, 'runId');
+  if (runId === null) {
+    log.error((ctx.body as any).error);
+    return;
+  }
+
   const start = startRequest();
 
   ctx.body = await getMeasurements(
     ctx.params.projectSlug,
-    Number(ctx.params.runId),
+    runId,
     ctx.params.baseId,
     ctx.params.changeId,
     db
   );
 
-  ctx.type = 'application/json';
   completeRequestAndHandlePromise(start, db, 'get-measurements');
 }
 
diff --git a/src/backend/main/main.ts b/src/backend/main/main.ts
index c0287596..95317faa 100644
--- a/src/backend/main/main.ts
+++ b/src/backend/main/main.ts
@@ -15,6 +15,8 @@ import {
 import type { AllResults } from '../../shared/api.js';
 import { Database } from '../db/db.js';
 import { TimedCacheValidity } from '../db/timed-cache-validity.js';
+import { getNumberOrError } from '../request-check.js';
+import { log } from '../logging.js';
 
 const mainTpl = prepareTemplate(robustPath('backend/main/index.html'), false);
 
@@ -34,11 +36,16 @@ export async function getLast100MeasurementsAsJson(
   ctx: ParameterizedContext,
   db: Database
 ): Promise<void> {
-  const start = startRequest();
-
-  ctx.body = await getLast100Measurements(Number(ctx.params.projectId), db);
   ctx.type = 'application/json';
 
+  const projectId = getNumberOrError(ctx, 'projectId');
+  if (projectId === null) {
+    log.error((ctx.body as any).error);
+    return;
+  }
+
+  const start = startRequest();
+  ctx.body = await getLast100Measurements(projectId, db);
   completeRequestAndHandlePromise(start, db, 'get-results');
 }
 
@@ -166,8 +173,15 @@ export async function getChangesAsJson(
   ctx: ParameterizedContext,
   db: Database
 ): Promise<void> {
-  ctx.body = await getChanges(Number(ctx.params.projectId), db);
   ctx.type = 'application/json';
+
+  const projectId = getNumberOrError(ctx, 'projectId');
+  if (projectId === null) {
+    log.error((ctx.body as any).error);
+    return;
+  }
+
+  ctx.body = await getChanges(projectId, db);
 }
 
 export async function getChanges(
diff --git a/src/backend/project/data-export.ts b/src/backend/project/data-export.ts
index d447afbd..522e13f7 100644
--- a/src/backend/project/data-export.ts
+++ b/src/backend/project/data-export.ts
@@ -7,6 +7,7 @@ import { dbConfig, siteConfig, storeJsonGzip } from '../util.js';
 import { log } from '../logging.js';
 import { Database } from '../db/db.js';
 import { ParameterizedContext } from 'koa';
+import { getNumberOrError } from '../request-check.js';
 
 const expDataPreparation = new Map();
 
@@ -98,8 +99,15 @@ export async function getAvailableDataAsJson(
   ctx: ParameterizedContext,
   db: Database
 ): Promise<void> {
-  ctx.body = await getDataOverview(Number(ctx.params.projectId), db);
   ctx.type = 'application/json';
+
+  const projectId = getNumberOrError(ctx, 'projectId');
+  if (projectId === null) {
+    log.error((ctx.body as any).error);
+    return;
+  }
+
+  ctx.body = await getDataOverview(projectId, db);
 }
 
 export async function getDataOverview(
diff --git a/src/backend/request-check.ts b/src/backend/request-check.ts
new file mode 100644
index 00000000..90b0d578
--- /dev/null
+++ b/src/backend/request-check.ts
@@ -0,0 +1,19 @@
+import { ParameterizedContext } from 'koa';
+
+export function getNumberOrError(
+  ctx: ParameterizedContext,
+  paramName: string
+): number | null {
+  const value = Number(ctx.params[paramName]);
+
+  if (isNaN(value)) {
+    ctx.status = 400;
+    ctx.body = {
+      error: `Invalid ${paramName} provided. Received "${ctx.params.runId}".`
+    };
+
+    return null;
+  }
+
+  return value;
+}
diff --git a/src/backend/timeline/timeline.ts b/src/backend/timeline/timeline.ts
index aa15f1cd..b3aa2ad1 100644
--- a/src/backend/timeline/timeline.ts
+++ b/src/backend/timeline/timeline.ts
@@ -7,6 +7,8 @@ import { prepareTemplate } from '../templates.js';
 import { TimelineSuite } from '../../shared/api.js';
 import { Database } from '../db/db.js';
 import { robustPath } from '../util.js';
+import { getNumberOrError } from '../request-check.js';
+import { log } from '../logging.js';
 
 const timelineTpl = prepareTemplate(
   robustPath('backend/timeline/timeline.html'),
@@ -17,14 +19,24 @@ export async function getTimelineAsJson(
   ctx: ParameterizedContext,
   db: Database
 ): Promise<void> {
-  ctx.body = await db.getTimelineForRun(
-    Number(ctx.params.projectId),
-    Number(ctx.params.runId)
-  );
+  ctx.type = 'application/json';
+
+  const projectId = getNumberOrError(ctx, 'projectId');
+  if (projectId === null) {
+    log.error((ctx.body as any).error);
+    return;
+  }
+
+  const runId = getNumberOrError(ctx, 'runId');
+  if (runId === null) {
+    log.error((ctx.body as any).error);
+    return;
+  }
+
+  ctx.body = await db.getTimelineForRun(projectId, runId);
   if (ctx.body === null) {
     ctx.status = 500;
   }
-  ctx.type = 'application/json';
 }
 
 /**