NestJS Doctor vs Nest Devtools

Both tools draw a NestJS module graph. They get there from opposite ends.

Nest Devtools boots your application and introspects the graph Nest built. nestjs-doctor reads the @Module() decorators in your source and never runs anything. Neither approach contains the other, so this page covers what each one can see.

How each one gets the graph

Nest Devtools takes a DevtoolsModule import plus a snapshot flag on NestFactory.create. The running app then exposes an extra HTTP server, on port 8000 by default, and the dashboard at devtools.nestjs.com reads the graph from it. Nest's own documentation says not to enable the module in production.

nestjs-doctor takes one command:

npx nestjs-doctor@latest . --report

That writes a single HTML file and opens it. Nothing boots, so a module that cannot start, because a provider is missing, still shows up in the graph with the problem named.

	Nest Devtools	nestjs-doctor
Setup	A module import and a factory flag	One command
The app has to run	Yes	No
Reads the graph from	A local HTTP server	Your source files
Shows the graph Nest built at runtime	Yes	No, it infers it from decorators

Boot times

Both show you where startup went. Devtools has a bootstrap performance analyzer. --timings overlays per-class construction times on the module graph in the report.

They read the same artifact. --timings takes the SerializedGraph that Nest itself produces, which is the same dump Devtools introspects, so a Devtools user already has what it needs. Boot trace covers capturing one.

Rules and custom rules

This is the widest gap, and it runs both ways at first glance. Devtools does analyze your graph, and its findings carry error, warning and info severities. There are 11 checks, all architecture heuristics, with thresholds fixed in the product.

nestjs-doctor runs 52 rules across security, correctness, architecture, performance and schema. Every one can be disabled, ignored per line, or replaced, and you can add your own against your own conventions.

	Nest Devtools	nestjs-doctor
Checks	11	52
Categories	Architecture	Security, correctness, architecture, performance, schema
Thresholds	Fixed in the product	Configurable per rule
Adding a check	The shipped set	Write one in a TypeScript file
A finding points at	A node in the graph	A file and a line
Summary	Counts by severity	Counts plus a 0 to 100 score

See Rules for the full list and Custom rules for writing one.

The database schema

The Devtools graph is Nest's injector graph: modules, classes, entrypoints. It has no concept of a database.

nestjs-doctor extracts an entity-relationship diagram from Prisma, TypeORM, Drizzle and MikroORM, and reports three schema rules against the entity itself. Schema rules covers what it checks.

In CI

Devtools publishes serialized graphs to a central registry and shows a diff between builds. That integration sits on the Enterprise plan, and it reports rather than gates.

nestjs-doctor is built to fail a build. --blocking gates on severity, --min-score gates on the score, and the GitHub Action comments only on what a pull request introduced. Failing the build covers the flags.

Everything is free

There is no paid tier and no seat count. Everything ships under MIT:

The CLI and all 52 rules, plus the rules you write yourself.
The HTML report: module graph, endpoint traces, ER diagram and boot trace.
The GitHub Action that reviews pull requests.
The VS Code extension and the language server.
The skills for coding agents.

Nest Devtools is a paid product with a short trial.

Running both

Nothing here requires a choice. DevtoolsModule stays in your app for the runtime questions, and nestjs-doctor runs in CI on every pull request, where Devtools does not gate anything.

Start with a scan and read the score:

npx nestjs-doctor@latest .

Quickstart covers reading the output, and GitHub Actions setup covers putting it on pull requests.