Tamper Data Chrome Here

body 
  width: 400px;
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  margin: 0;
  padding: 0;
  background: #1e1e2f;
  color: #cdd6f4;
.container 
padding: 16px;

h2 
margin: 0 0 8px;
font-size: 20px;
color: #89b4fa;

h3 
font-size: 14px;
margin: 16px 0 8px;
color: #bac2de;

hr 
border: none;
border-top: 1px solid #313244;
margin: 12px 0;

label 
display: block;
font-size: 12px;
margin: 8px 0 4px;
font-weight: bold;

input 
width: 100%;
padding: 8px;
background: #313244;
border: 1px solid #45475a;
color: #cdd6f4;
border-radius: 6px;
box-sizing: border-box;
font-size: 12px;
 tamper data chrome
button 
margin-top: 12px;
background: #89b4fa;
color: #1e1e2f;
border: none;
padding: 8px 12px;
border-radius: 6px;
cursor: pointer;
font-weight: bold;
width: 100%;

button:hover 
background: #b4befe;

ul 
list-style: none;
padding: 0;
max-height: 250px;
overflow-y: auto;

li 
background: #313244;
margin: 8px 0;
padding: 8px;
border-radius: 6px;
font-size: 12px;
word-break: break-all;

.deleteBtn 
background: #f38ba8;
color: #1e1e2f;
font-size: 11px;
padding: 4px 8px;
margin-top: 6px;
width: auto;
display: inline-block;
 ModHeader extension (modify headers)
#noRules 
color: #6c7086;
text-align: center;
padding: 20px;
font-style: italic;

For true "tamper data" behavior (pause, edit, resume), use Caido, Burp Suite, or mitmproxy.

While the original Tamper Data was a standalone legacy extension, its spiritual successor for the modern web is Tamper Chrome.

Unlike the old toolbar-based interfaces, Tamper Chrome integrates directly into the Chrome Developer Tools. It provides a clean interface for intercepting requests, but it requires a bit of setup. Requestly (modify requests/responses)

How to use it:

Once enabled, you can pause the request execution, edit headers, modify POST data, and forward the request to the server. It effectively replicates the core mechanic of the original tool: Client-side interception.