A visual feedback tool for web apps that works behind the login
A visual feedback tool for web apps lets a reviewer click a screen inside your app and leave a comment pinned to that element, with a screenshot and the technical context a developer needs. The hard part is the login: most of a web app sits behind one, and a tool that shows reviewers a copy of your pages stops at the sign-in screen. Tools get past it in one of two ways. A browser extension works wherever the reviewer is signed in, but every reviewer installs it. A script snippet in your app loads the real thing for everyone with nothing to install. Layerdock uses a snippet; this page explains the trade-off and how it works.
Why a web app is harder to review than a website
- The login. Dashboards, settings and checkout only exist for a signed-in user, so the tool has to run in a session your app accepts.
- State. The bug is often on a screen you reach by clicking, not by URL: a half-filled form, an open modal, an empty state. The pin has to remember the element, not just the address.
- Environments. Review usually happens on staging or a preview deploy, not production, and that host changes from build to build.
- Reviewers. Clients and product owners will open a link; far fewer will install an extension or create another account.
Three ways a feedback tool reaches your app
| Approach | Behind the login | What the reviewer installs | Examples |
|---|---|---|---|
| A copy served from the vendor | Usually stops at the sign-in screen | Nothing | Most URL-review tools, including Layerdock without its snippet |
| Browser extension | Yes, wherever the reviewer is signed in | The extension, on every reviewer’s browser | Ybug, Jam.dev, Simple Commenter, Userback, BugHerd, Bird Eats Bug |
| Script snippet or widget in your app | Yes, for anyone who can sign in | Nothing; you add one tag once | Layerdock, Ybug, Simple Commenter, Marker.io, Userback, PageProofer, Feedbucket, BugHerd, Usersnap |
Examples are taken from how each vendor describes its own capture method in our website feedback tools comparison, read 26 October 2026. Several tools offer more than one; check the vendor’s docs for whether its widget runs in a signed-in session of your app.
The extension route suits an in-house QA team who all use the same browser. The snippet route suits client review, where you control the app but not the reviewer’s machine.
How Layerdock reviews a web app
- Create a dock and choose Web app. Step 2 shows the dock’s snippet: one
<script>tag. - Add it to your app’s shared layout, or press Copy AI prompt and paste it into Claude Code or Cursor, which adds it for you and changes nothing else.
- Send the review link. The dock loads your real app, reviewers sign in as they normally would, and every pin lands on the element they clicked, on the page they were on.
- If your app refuses to be shown in a frame, or a browser drops the login inside the review (Safari does), Open on live site opens the same page in a new tab with a Layerdock toolbar. Pins go to the same review.
Staging and preview hosts can be added to the dock, so the same snippet works across environments. The step-by-step setup, per framework, is in review a web app.
What each pin carries
- The element, the page and a screenshot, so a developer can find it without asking.
- Browser, screen size and system details.
- Console errors and network requests from the moment of the pin, captured on every plan and readable on Agency (see how diagnostics capture works).
- Screen recordings on Pro and Agency, for bugs that only show in motion.
- On Pro and Agency, a hand-off to Claude Code or Cursor over MCP, so a coding agent can read the pin and fix it (see AI bug fixing).
What your real users get
Nothing. For an ordinary visitor the snippet does nothing after the script file loads: no element on the page, nothing stored in the browser, no requests. It wakes up only inside a Layerdock review. The key in the tag is public by design and cannot read or write feedback on its own.
Questions to ask any web app feedback tool
- Does it work on pages behind my login, and how: extension, snippet or proxy?
- Do reviewers install anything or create an account?
- Does the snippet do anything for users who are not reviewing?
- Can one setup cover staging, preview deploys and production?
- Which plan includes console and network capture?
- Can feedback go straight to my issue tracker or coding agent?
Common questions
What is the best visual feedback tool for a web app?
One that reaches the pages behind your login without asking every reviewer to install something. A script snippet in your app does that: the reviewer signs in as usual and pins comments on the real screens. Layerdock works this way with one tag, and its review link also covers public pages with no snippet at all. Marker.io and Userback also install as a script widget; extension tools work wherever the reviewer is signed in, but each reviewer installs the extension.
Can clients leave feedback on a web app without an account?
On Layerdock, yes. A client opens the review link, signs in to your app if it asks, and pins comments without a Layerdock account or any install. Your app’s own login still applies, so they need whatever access your app requires.
Does the snippet slow down my app or track my users?
For an ordinary visitor the Layerdock snippet does nothing after the script file loads: it adds nothing to the page, stores nothing and sends no requests. It only starts inside a Layerdock review or for a reviewer who arrived from one.
Can a coding agent fix the feedback?
Yes. On Pro and Agency, Claude Code, Cursor and other MCP clients can read each pin with its element, page and screenshot, fix it and mark it resolved. Console errors and network requests reach the agent on Agency.
Reviewing a marketing site instead? No snippet needed: see the website feedback tools comparison. For QA on a build, read the website QA testing tool page, or start with Layerdock free; the snippet works on every plan.