Your coding agent can't fix what it can't see.
Replay captures the full browser runtime — every DOM change, network request, and state update — and turns it into a root cause and a specific fix. No manual debugging.
Trusted by top engineering teams
Your agent reads code.
It can't read the runtime.
A test fails. A user hits a bug. Your agent takes a guess at the fix, pushes it, and the same test fails again. Without runtime context, agents are stuck in a loop — guessing, patching, retrying.
The problem isn't the agent. It's that the agent has no way to see what actually happened in the browser. No DOM state, no network timing, no component re-renders. It's debugging blind.
You end up pulling the agent aside, opening DevTools yourself, and spending an hour doing the work manually. The whole point of the agent was to save you that time.
That's why we built Replay
Give your agent eyes
on the runtime
Replay records a deterministic capture of your browser session — every DOM change, network request, and state update. It analyzes the recording, identifies the root cause, and delivers a detailed fix directly to your coding agent via MCP, or in plain English via the Chrome extension.
Works where you already work.
Same recording engine. Two ways to connect.
Replay MCP
Install Replay MCP in one command and connect it to Cursor, Claude Code, Copilot, or Windsurf. Your agent gets root cause and a specific fix automatically.
Read the docs →Replay Chrome Extension
Record a bug in your browser, get a plain-English fix to paste into your AI tool. No setup required.
Coming SoonFrom bug to fix — without touching DevTools
See how Replay MCP lets your agent dive in and explain the problem.
Button doesn't work
Creating a new task does nothing
Chat transcript with Replay MCP
The form to add a new task isn't doing anything
I'll investigate why the form to add a new task isn't working. Let me start by exploring the recording to understand what's happening.
Let me look at the CreateTaskModal component more closely to understand its implementation, especially the form submission logic.
I can see the form submission logic. Line 53-54 shows handleSubmit was called once, but let me check where the onSave callback leads to. Let me look at TasksListPage to see how the modal's onSave is handled.
I found the issue! Looking at handleCreateTask (lines 73-93):
- Line 83 shows the function was called once (hit count: 1)
- Lines 84-90 build the payload object
- Line 92 closes the modal with
setCreateModalOpen(false)(hit count: 1) - But there's no
fetchcall to actually save the task!
The function closes the modal at the end, but it never makes a network request to persist the new task. The payload is built but never sent to the server.
Root Cause
The handleCreateTask function in TasksListPage.tsx is missing the API call to create the task. It:
- Builds the payload object ✓
- Closes the modal ✓
- Does NOT call
fetchto POST the task to the backend ✗
Compare this to line 65-70 where fetch is used to load deals - a similar pattern should exist after building the payload on line 92, but it's missing. The function just closes the modal without actually saving anything.
What your agent gets from Replay
Three things Replay delivers on every bug.
Root-cause analysis, automated
Replay doesn't just report the error. It traces through the recording to find the exact cause — the state change, the failed request, the bad render — and explains why it happened.
Detailed fixes, not vague suggestions
Your agent receives a specific, implementation-ready fix with full context — which file, which function, what to change, and why. No more trial-and-error loops.
Works with any coding agent
Replay MCP connects to Claude Code, Cursor, Copilot, Windsurf, and any agent that supports MCP. Add it once and every agent in your workflow gets full runtime visibility.
Case Studies
Hear from Replay teams directly
“Before Replay We spent somewhere between 1–2 hours per day per dev in this reproducibility purgatory. The toll this was taking on our development velocity and our ability to respond and resolve issues was huge. We thought there must be a better way.”
Read full case study
Mark Probst
@VP Eng, Glide
“If I didn’t have Replay, it would have taken me several days or even weeks getting the debugger to run properly in all the dynamically loaded scripts, which is not easy. With Replay it took me half a day to figure it out and get a fix ready.”
Read full case study
Simeon Cheeseman
@Tablecheck, Principal Engineer
“The tools that we were using before were barely better than useless. You’d say thanks for the console log screenshot and spend 2–3 days trying to recreate the issues and finding it in the code. With Replay, all that wasted time has been eliminated.”
Read full case study
Shane Duff
@Pantheon, Front End Lead
Testimonials
See what time travelers are saying
“Next.js App Router is now stable in 13.4. Wouldn’t have been possible without Replay, we investigated so many (over 20) super complicated bugs that using traditional debugging would have cost us days to investigate.”
Tim Neutkins
@Co-author of Next.js
“I think Replay has a very good chance of creating a new category around collaborative debugging”
Guillermo Rauch
@Founder of Vercel
“When I see a hard-to-reproduce issue in GitHub, I ask for a replay.”
JJ Kasper
@Co-author of Next.js
“If I don't immediately know the answer to a bug, I immediately reach for Replay.io. It's like HMR for repros.”
Sebastian Markbåge
@React Maintainer
“Replay.io is galaxy brain tooling. Real gamechanger.”
Dan Abramov
@React Maintainer
“I think Replay has a very good chance of creating a new category around collaborative debugging”
Guillermo Rauch
@Founder of Vercel
“When I see a hard-to-reproduce issue in GitHub, I ask for a replay.”
JJ Kasper
@Co-author of Next.js
“If I don't immediately know the answer to a bug, I immediately reach for Replay.io. It's like HMR for repros.”
Sebastian Markbåge
@React Maintainer
“Replay.io is galaxy brain tooling. Real gamechanger.”
Dan Abramov
@React Maintainer
“Programmers typically reach for debuggers when they run out of ideas on how to fix their code. Now coders reach for time-travel debugging to understand their programs and not just when they want to fix a bug.”
Amjad Masad
@Founder Replit
“Fast forwarding and rewinding to breakpoints has saved me days(weeks??) while hunting down issues in @solid_js interruptible concurrent rendering.”
Ryan Carniato
@Solid Founder
“Replay.io gives me the tools I need to solve seemingly impossible bugs. It’s like the Redux DevTools, but for every line of code in your app.”
Mark Erikson
@Redux Maintainer
“Replay.io allows me to debug problems that would be impossible to debug by traditional means - it has saved me from countless hours of confusion and frustration.”
Lenz Weber-Tronic
@Redux Toolkit Maintainer
“I’m not sure if we could’ve shipped the last major version of RedwoodJS without Replay.”
Dom Saadi
@Maintainer of RedwoodJS
“Replay.io is so great! Today I had a hard-to-repro flow in development, so I recorded a replay to see how it works. I didn’t only find the bug, I discovered a performance improvement using Replay.”
Ives van Hoorne
@Co-founder CodeSandbox
“Current status: time-travel debugging Typescript's compiler. Replay is the hero tool I don't deserve. My dev life consists of 2 major eras now - I call them pre-Replay and post-Replay.”
Mateusz Burzyński
@OSS Contributor to Typescript
“Replay.io is from another planet where bug reports save you time, instead of eating up hours of debugging.”
Matt Pockock
@Full-time TypeScript educator
“Time travel is the obvious next step for the future of collaboratively inspecting and debugging applications.”
David Khourshid
@Founder of Stately.ai
“People use the word "game-changer" waaaaay too often. Very rarely does anything change the game. But this just might! I'm sharing it to all of my teams.”
Erik Rasmussen
@Author of Redux form and final form
“Replay.io is one of these experiences that first feels like magic – but after squashing your first bugs with it, you will quickly wonder how you ever worked without it”
Harald Kirschner
@Product Manager, VS Code
“Replay.io is the most significant leap forward for debugging since we introduced the step debugger”
Kenneth Auchenberg
@Developer Products, Stripe
“If a picture is worth a thousand words, a replay is worth a thousand pictures”
Zack Rosen
@CEO of Pantheon
“Recording and debugging flaky tests with Replay.io feels like hopping in Doc Brown’s DeLorean and flying back to the time of the crash!”
Gleb Bahmutov
@Distinguished Engineer, Cypress
“Before Replay.io, we spent somewhere between 1–2 hours per day per dev in this reproducibility purgatory”
Mark Probst
@Glide apps, VP Eng
Built for teams shipping with agents
Wherever your agent gets stuck on a bug it can't see, Replay closes the gap.
Agent-assisted development
Your coding agent hits a failing test or runtime error. Instead of looping, it sends the recording to Replay and gets a precise fix back — then implements it.
Flaky tests in CI
Record every test run. When a test flakes, Replay analyzes the recording and delivers the root cause and fix to your agent — no manual investigation needed.
Bug triage on autopilot
A user reports a bug. Replay captures the session, generates the diagnosis and fix. Your agent applies it. You review the PR.
Unblocking stuck agents
When your agent loops on a problem — retrying the same patch, failing the same test — Replay gives it the runtime context it needs to break out.
Replay vs. the old way
Without Replay
- Agent guesses at the fix, fails, retries in a loop
- You step in to debug manually with DevTools
- Flaky tests get retried and ignored
- Bug reports sit in the backlog waiting for someone to reproduce them
- Agents write code fast but can't debug what they break
With Replay
- Agent gets a detailed fix from the recording on the first try
- You review the PR instead of opening DevTools
- Flaky tests get diagnosed and fixed automatically
- Bug reports get a recording, analysis, and fix in minutes
- Agents ship fixes as fast as they ship features
Common questions
Stop debugging for your agent.
Let Replay do it.
Free to get started. No credit card required.