diff --git a/apps/sim/tools/http/request.test.ts b/apps/sim/tools/http/request.test.ts
index 661239c7cbd..df59cabbd85 100644
--- a/apps/sim/tools/http/request.test.ts
+++ b/apps/sim/tools/http/request.test.ts
@@ -70,6 +70,43 @@ describe('HTTP Request Tool', () => {
       expect(url.includes('chars')).toBe(true)
     })
 
+    it.concurrent('substitutes path parameters only by their whole name', () => {
+      expect(processUrl('https://www.google.com', { '': '' })).toBe('https://www.google.com')
+      expect(processUrl('https://api.example.com:8443/users/:id', { '8443': 'x', id: '42' })).toBe(
+        'https://api.example.com:8443/users/42'
+      )
+      expect(processUrl('https://api.example.com/users/:idx/:id', { id: '1', idx: '2' })).toBe(
+        'https://api.example.com/users/2/1'
+      )
+      expect(processUrl('https://api.example.com/users/:id-profile', { id: '7' })).toBe(
+        'https://api.example.com/users/7-profile'
+      )
+      expect(processUrl('https://api.example.com/users/:user-id', { 'user-id': '9' })).toBe(
+        'https://api.example.com/users/9'
+      )
+      expect(processUrl('https://api.example.com/users/:id', { id: '$&' })).toBe(
+        'https://api.example.com/users/%24%26'
+      )
+      expect(processUrl('https://api.example.com/users/:user.name', { 'user.name': 'ada' })).toBe(
+        'https://api.example.com/users/ada'
+      )
+      expect(processUrl('https://api.example.com/v1/:$ref', { $ref: 'x' })).toBe(
+        'https://api.example.com/v1/x'
+      )
+      expect(processUrl('https://api.example.com/users/:id', { '/': 'x', '1': 'y' })).toBe(
+        'https://api.example.com/users/:id'
+      )
+      expect(
+        processUrl('https://api.example.com/:user-id/:user', { user: 'alice', 'user-id': '42' })
+      ).toBe('https://api.example.com/42/alice')
+      expect(
+        processUrl('https://api.example.com/:user.name', { user: 'alice', 'user.name': 'ada' })
+      ).toBe('https://api.example.com/ada')
+      expect(processUrl('https://api.example.com/:é/:éa', { é: '42', éa: '7' })).toBe(
+        'https://api.example.com/42/7'
+      )
+    })
+
     it.concurrent('canonicalizes first-party API calls before the apex redirect', () => {
       expect(
         processUrl('https://sim.ai/api/v2/workflows', undefined, [
diff --git a/apps/sim/tools/http/utils.ts b/apps/sim/tools/http/utils.ts
index 22cba3b2647..0495fb3073c 100644
--- a/apps/sim/tools/http/utils.ts
+++ b/apps/sim/tools/http/utils.ts
@@ -1,3 +1,4 @@
+import { escapeRegExp } from '@/executor/constants'
 import { transformTable } from '@/tools/shared/table'
 import type { TableRow } from '@/tools/types'
 
@@ -81,6 +82,37 @@ export const getDefaultHeaders = (
   return headers
 }
 
+/**
+ * A path parameter key must start like a JavaScript identifier, using the same character classes
+ * path-to-regexp uses for `:name` parameters. That excludes an empty key and one starting with a
+ * digit or `/`, the shapes that matched the scheme separator or a port; the rest of the key is left
+ * as callers use it.
+ */
+const PATH_PARAM_KEY = /^[$_\p{ID_Start}][^\s/?#]*$/u
+const PATH_PARAM_NAME_CONTINUE = '[$\\u200c\\u200d\\p{ID_Continue}]'
+
+/**
+ * Replaces the first `:key` placeholder for each path parameter with its URL-encoded value.
+ *
+ * A placeholder ends where an identifier would, so `:id` never matches inside `:idx`, and longer
+ * keys are substituted first, so `:user-id` is not consumed by a `user` key. A plain string replace
+ * let an empty key strip the scheme's colon (`https://` became `https//`), a numeric key rewrite a
+ * port, and `:id` match inside `:idx`.
+ */
+function substitutePathParams(url: string, pathParams: Record<string, string>): string {
+  const entries = Object.entries(pathParams)
+    .filter(([key]) => PATH_PARAM_KEY.test(key))
+    .sort(([a], [b]) => b.length - a.length)
+  let substituted = url
+  for (const [key, value] of entries) {
+    substituted = substituted.replace(
+      new RegExp(`:${escapeRegExp(key)}(?!${PATH_PARAM_NAME_CONTINUE})`, 'u'),
+      () => encodeURIComponent(value)
+    )
+  }
+  return substituted
+}
+
 /**
  * Processes a URL with path parameters and query parameters
  * @param url Base URL to process
@@ -98,9 +130,7 @@ export const processUrl = (
   }
 
   if (pathParams) {
-    Object.entries(pathParams).forEach(([key, value]) => {
-      url = url.replace(`:${key}`, encodeURIComponent(value))
-    })
+    url = substitutePathParams(url, pathParams)
   }
 
   if (queryParams) {