Fiddler Everywhere is a web debugging proxy that captures HTTP and HTTPS traffic between an application and the internet, letting developers inspect requests, edit responses, mock endpoints, and replay API calls from a single desktop workspace.
Fiddler Everywhere sits between an application and the servers it talks to, recording every HTTP and HTTPS request and response that passes through. Turn on capturing, reproduce the problem, and the session list shows what was actually sent: headers, bodies, cookies, status codes, timing, and certificate details. From there you can filter down to the endpoints that matter, save the session as a snapshot, or set a breakpoint to pause traffic and change it in flight. The same workspace doubles as an API client, so a captured request can be edited and resent to test a fix. Nothing leaves the machine unless you deliberately share it.
Fiddler Everywhere is used by front-end and back-end developers, QA engineers, and support teams who need to explain why a page or an app misbehaves. A front-end developer confirms whether a field is missing from the response, a QA engineer mocks an error to check how the interface handles it, and a support engineer captures a customer's failing request without asking for a screen recording. Sessions and rules can be shared with colleagues, so the evidence travels with the ticket. It works one layer above a bandwidth tool such as NetWorx, which reports how much data a connection moves rather than what the requests contained.
Fiddler Everywhere replaces guesswork with the actual bytes that crossed the wire. When a log says one thing and a server says another, the captured request settles the argument in seconds, which is worth more than an hour of reading code and speculating. Rules and breakpoints let a developer reproduce an error response on demand, so edge cases can be tested without waiting for a production outage, and the API composer turns a one-off captured call into a repeatable request for regression checks. Because sessions can be saved, filtered, and shared, a bug report becomes a file a colleague can open rather than a description someone has to reconstruct. Support for modern protocols and encrypted traffic means the same tool covers today's APIs and yesterday's legacy services.
Key capabilities and highlights.
Fiddler Everywhere records every request and response that passes through the proxy, including encrypted traffic once the certificate is trusted. Capturing can run at the system level, inside a browser, or from a terminal, so the tool fits into whichever workflow the developer already uses.
Custom rules can rewrite headers, redirect a request to another host, or replace a response body with a prepared payload, and breakpoints pause traffic so it can be edited by hand. Mocking an endpoint this way tests error handling without touching the server.
Fiddler Everywhere can build requests from scratch, adjust them from a captured session, save them into collections, and execute them again at any time. That turns exploratory debugging into a repeatable API check the whole team can reuse when a service changes.
Fiddler Everywhere groups traffic by process, and it can be narrowed by host, status code, content type, or size, with multiple filtering approaches available. On a busy page, that is the difference between scrolling through hundreds of rows and finding the failing request immediately.
Each session exposes headers, bodies, cookies, raw text, timing, transfer size, TLS version, and certificate information, with HEX and protocol-specific decoders for binary payloads. Those details are usually what settles an argument between two teams, and they are readable without extra tooling.
Beyond plain HTTP, the tool decodes HTTP/2, WebSockets, gRPC, SignalR, Server-Sent Events, MessagePack, and Protobuf. Streaming APIs and real-time features that older proxies display as unreadable noise can be inspected like any other request, which matters when a chat, feed, or dashboard depends on them.
Fiddler Everywhere saves captured sessions as snapshots that can be organized for later and shared with colleagues, so a bug reaches the right person with the evidence attached. Sharing traffic beats describing a failure over chat, especially for intermittent problems.
Traffic from phones, tablets, and other machines can be routed through the proxy for debugging away from the desktop, and a built-in assistant plus MCP integration lets AI tools query captured sessions. Reverse proxy mode covers traffic to local or remote servers.
Browse historical releases and previous builds.
Common questions about Fiddler Everywhere.
It captures and inspects HTTP and HTTPS traffic so developers can see exactly what an application sent and received. Common uses include debugging failed API calls, checking headers and authentication tokens, mocking error responses, testing services with repeated requests, and gathering evidence for a support ticket.
Yes, encrypted sessions can be decrypted for inspection once the tool's certificate is trusted by the application or operating system making the requests. That is what makes it possible to read request bodies and headers that would otherwise appear only as unreadable cipher text.
A free tier is available for individual use with limits on some team and automation features, while paid plans add collaboration, advanced rules, and commercial support. Teams should check the current comparison to confirm which option covers their debugging and support requirements.
Yes. Traffic from a phone or tablet can be routed through the same proxy, so requests from a mobile app can be captured alongside desktop traffic. That is useful when a bug appears only on one device, one network, or one operating system version.
A bandwidth monitor counts how much data a connection transfers and reports speeds, while Fiddler Everywhere breaks that traffic down into individual requests and responses. One answers how much, the other answers what exactly was sent, so the two are usually used side by side.
Fiddler Everywhere is a web debugging proxy that captures HTTP and HTTPS traffic between an application and the internet, letting developers inspect requests, edit responses, mock endpoints, and replay API calls from a single desktop workspace.
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