Log inSubmit server
Loopback logo

Loopback

Collects web-app feedback with context, then lets coding agents claim, fix, verify, and resolve queued items over MCP.

InstallRepositoryWebsite
Full README Compare alternatives Embed widget Claim this listing

Install Loopback

Pick your client, then add it in one click or paste the config.

STDIONode.js
~/Library/Application Support/Claude/claude_desktop_config.json
claude_desktop_config.json
{
  "mcpServers": {
    "loopback": {
      "command": "npx",
      "args": [
        "-y",
        "loopback-mcp-server"
      ]
    }
  }
}

Settings → Developer → Edit Config, merge this into mcpServers, then fully quit and reopen Claude Desktop.

Install not yet sandbox-tested— we haven't run this command through our automated sandbox yet. Not a red flag; we're working through the catalog.

Overview

The loopback MCP server connects local web apps, a shared SQLite feedback queue, and coding agents through MCP. A browser widget lets users pin comments to elements while capturing console output, failed requests with response bodies, route history, and optional AI run metadata. Agents can work project-scoped queues over stdio or streamable HTTP, and status changes appear back on the page as pins turn green. Reach for it when feedback from real app usage needs to become actionable work for Claude Code, Codex, or Gemini CLI.

Use cases

  • Pin a broken form directly on a local web app
  • Route captured browser failures into a project queue
  • Let coding agents claim and resolve feedback items
  • Verify fixes from the running page
  • Submit feedback from CI or scripts with /ingest

Key features

  • Element-anchored browser feedback pins
  • Console and failed-request capture
  • Shared project-tagged SQLite queue
  • MCP access over stdio and streamable HTTP
  • Agent claims, status updates, and linked changes
  • Green pin write-back after verification

Security & health

What it can reach and how reliably it runs — from our own checks, not the maintainer’s claims.

ActiveLast checked 2d ago

Recent health check succeeded.

Supply-chain signal

No high-severity advisories surfaced by our automated scan.

Critical 0High 0Medium 0Low 0

Scanned 14d ago via OSV.dev · loopback-mcp-server (npm)

Adoption & maintenance

Factual signals from GitHub, npm, and our automated checks — not a rating.

npm downloads227Package downloads in the last 30 days.
Last commit2mo agoMost recent push to the default branch.

How Loopback works

What loopback MCP server does

The loopback MCP server turns feedback on a running web application into items that coding agents can process. A widget adds a toolbar and element-anchored pins to an app, allowing someone to describe a problem directly on the affected page. Each item is associated with a project slug and stored in a shared SQLite database at ~/.loopback/loopback.db.

A pin can include more than its written description. The widget records relevant console output, the route journey leading to the issue, failed network requests and their response bodies, typed reproduction steps, and available LLM run metadata such as a run ID, model, or trace URL. Publicly deployed sites can submit items through /ingest instead of using the widget.

How it works

Run the server separately for each agent over stdio, or keep one HTTP instance running on 127.0.0.1:7077. The HTTP mode is required by the browser widget and exposes the MCP endpoint at http://127.0.0.1:7077/mcp. Multiple agents and projects can use the same local database, with project slugs separating their queues.

The agent workflow is organized around a feedback lifecycle: list items, claim one, investigate and fix it, link the resulting change, mark it fixed, verify the result, and resolve the item. The web queue at /queue provides a human-readable view, while item pages support comments and manual status changes. Once an item is verified, the corresponding page can update its pin to green and show the linked change.

Setup and configuration

Node.js 22.13 or newer is required because the project uses the built-in node:sqlite. Installation can use the published package through npx, or the repository can be cloned and built with npm install.

Register npx -y loopback-mcp-server as an MCP server in the agent configuration. Claude Code, Codex, and Gemini CLI each have documented registration paths. For a shared HTTP process, start loopback-mcp-server --http and keep it running with a process manager or operating-system service.

Add the widget script to an application with data-project set to the project slug and data-endpoint set to the local server URL. From the application repository, npx loopback-mcp-server init --project <slug> --write installs the project instructions and agent-specific configuration. The initialization is designed to be repeatable and non-destructive.

Tools and capabilities

The loopback MCP server supports agent access to:

  • Project-filtered feedback queues
  • Item details, comments, and status changes
  • Claiming work for an agent
  • Recording linked commits or pull requests
  • Marking fixes, verifying them, and resolving items
  • Feedback captured from widget pins or POST /ingest
  • Shared queue access across supported agents

The HTTP service also provides browser-facing queue pages, widget assets, and live status write-back used to update pins after verification.

Limitations and notes

This is primarily a local workflow: the documented HTTP service listens on 127.0.0.1:7077, and the default database is stored under the local user’s home directory. The widget requires the long-running HTTP mode; per-invocation stdio is intended for agents that spawn the server directly.

Other MCP clients may require their own configuration and are not described in the provided setup material. Public-site capture uses the /ingest route rather than assuming the local widget can reach the server. The server requires Node.js 22.13 or newer and is licensed under MIT.

Read the full README View source on GitHub

Reviews

No reviews yet — be the first to share how it worked for you.

Frequently Asked Questions about Loopback

loopback is an MCP server that connects local web apps to a shared feedback queue and coding agents. Its main tools support listing, claiming, commenting on, fixing, verifying, and resolving project items, while the browser widget captures element pins, console data, failed requests, route history, and available AI run metadata.

Install it with `npx -y loopback-mcp-server` in an MCP client configuration, or clone the repository and run `npm install`. Node.js 22.13 or newer is required. Start `loopback-mcp-server --http` when using the browser widget or a shared long-running instance.

Yes, loopback works with Claude Code through its MCP configuration. Register it with `claude mcp add --scope user loopback -- npx -y loopback-mcp-server`, or use the documented project configuration. Claude Code can also connect to the long-running streamable HTTP endpoint.

Add the widget script with `data-project` set to the project slug and `data-endpoint` pointing to the HTTP server. Start the server in HTTP mode, then use the Loopback toolbar to pin feedback on an element. Run `npx loopback-mcp-server init --project <slug> --write` from the repository.

Yes, scripts and CI can submit items with `POST /ingest`. The request includes `project`, `type`, `title`, and `body`. This route is also the documented capture path for deployed public sites and external pollers.

Related MCP servers

All in Coding Agents All alternatives
Add a badge to your READMEShow it’s listed — live SVG, Markdown or HTML.

AllMCPs Directory Badge

Full Badge Customizer

Showcase your server listing on GitHub or your project documentation. Embed this dynamic SVG badge to highlight official listing status and live engagement.

Badge Style:
Live Dynamic SVG PreviewLoopback AllMCPs Directory Badge
Markdown (GitHub README)
[![AllMCPs](https://allmcps.com/api/badge/loopback?style=directory)](https://allmcps.com/mcp/loopback)
HTML Embed
<a href="https://allmcps.com/mcp/loopback"><img src="https://allmcps.com/api/badge/loopback?style=directory" alt="Loopback on AllMCPs" /></a>