See everything your Node.js app is doing.
Lens is a framework-agnostic monitoring and debugging toolkit. Capture requests, database queries, cache, exceptions, mail, and jobs in one self-hosted dashboard.
npm install @lensjs/express @lensjs/watchersWorks with Express · Fastify · NestJS · Hono · Next.js · AdonisJS
import { lens } from "@lensjs/express";
import express from "express";
const app = express();
await lens({
app,
requestWatcherEnabled: true,
queryWatcher: {
enabled: true,
handler: createPrismaHandler({ provider: "postgresql" }),
},
});
// Dashboard is live at /lens
app.listen(3000);One toolkit for the whole request lifecycle
Lens captures the signals that matter and correlates them to a single request, so you can trace cause and effect without stitching tools together.
Requests
Every request with headers, body, response, status, duration, and the resolved user — redacted by default.
Database queries
Prisma, Kysely, Sequelize, MikroORM, Drizzle and Mongoose, correlated to the request that issued them.
Cache
Track hits, misses, writes and evictions across your caching layer with precise timing.
Exceptions
Automatic capture with stack traces, fingerprint grouping, and Slack / Discord / webhook alerts.
Audit outgoing email with rich MIME previews, iCalendar events, and attachments.
Jobs & queues
Watch BullMQ and Agenda jobs move through active, completed, and failed in real time.
A dashboard you'll actually enjoy using
Every signal, organized and correlated to the request that produced it — served right from your own app, with search, filters, and a live tail.
From zero to insight in three steps
- 1
Install the adapter
Add the adapter for your framework plus the watchers package.
- 2
Wire it up
Call lens() with your app instance and enable the watchers you want.
- 3
Open the dashboard
Visit /lens in your browser and watch requests stream in live.
npm install @lensjs/express @lensjs/watchersimport { lens } from "@lensjs/express";
import express from "express";
const app = express();
await lens({ app });
app.listen(3000);A focused, modular ecosystem
Install only what you need. Every package is published under the @lensjs/* scope with a stable, tree-shakable API.
The framework-agnostic engine: capture, context, store, API, and the bundled dashboard.
Express adapter — the reference integration for Lens.
Fastify adapter with request-lifecycle context and sampling.
NestJS adapter over Express or Fastify.
Hono adapter for edge-ready Node runtimes.
Next.js (App Router) adapter.
AdonisJS adapter following Adonis package conventions.
ORM & mailer handlers: Prisma, Kysely, Sequelize, MikroORM, Nodemailer and more.
Export captured signals as OpenTelemetry (OTLP) spans.
Model Context Protocol server so AI agents can read captured errors & requests.
Shared UTC producers and UI date presenters.