Adapters

An adapter is a protocol front door. Your client speaks the wire protocol it already knows — Convex, Firestore, Cloud Functions, MongoDB, DynamoDB, or the native API — and Nimbus serves it from the same engine, storage layer, and tenant boundary as every other surface. Picking a door changes the shape of your calls, not where your data lives or how it is isolated. The design and its limits are explained in the adapter boundary.

How the surfaces are served

Every server serves these surfaces by default. The Convex-compatible surface, the Firestore routes, and the native API share the main listener; MongoDB and DynamoDB each bind their own conventional port (127.0.0.1:27017 and 127.0.0.1:8000).

nimbus dev wires your app automatically, and it treats two kinds of surface differently.

One app adapter. The adapter that owns your app’s wiring, codegen, and watch loop is singular — exactly one is chosen:

Nimbus sees	App adapter
a convex/ directory	Convex
a firebase dependency	Firestore
a firebase.json	Cloud Functions

Any number of wire surfaces. These are a set, and they compose with any app adapter — a Convex app that also installs mongodb keeps its Convex dev loop and gets the MongoDB listener:

Runtime dependency	Wire surface
mongodb or mongoose	MongoDB — writes NIMBUS_MONGODB_URL to .env.local
@aws-sdk/client-dynamodb or @aws-sdk/lib-dynamodb	DynamoDB — writes NIMBUS_DYNAMODB_* to .env.local
@aws-sdk/client-s3 or @aws-sdk/lib-storage	S3

Wire-surface detection reads only the runtime dependencies in your package.json — not devDependencies, optionalDependencies, or peerDependencies — because enabling one starts a listener, generates credentials, and writes .env.local. A bare aws-sdk (v2) dependency is too broad to imply DynamoDB or S3, so it only produces a banner hint and never enables a surface.

The Firestore, MongoDB, DynamoDB, and S3 surfaces can each be switched off with nimbus start flags (--no-firestore, --no-mongodb, --no-dynamodb, --no-s3); the Convex-compatible surface and the native API are always on. Under nimbus dev a wire surface is enabled by its runtime dependency (above) rather than a flag — remove the dependency to leave it off. Flags, ports, and credentials are in configuration.

Which surface should you reach for?

Surface	Reach for it when	You write against	Migration guide
Convex	you want the full function model — queries, mutations, actions, and reactive subscriptions	convex/ functions and the Convex clients	Yes
Firestore	you have a Firebase app, or want Firestore’s document SDKs	the stock firebase/firestore SDK	Yes
Cloud Functions	you are porting Cloud Functions for Firebase workloads	firebase-functions v2 handlers	Yes
MongoDB	you already have code on the official MongoDB drivers	your existing MongoDB driver	—
DynamoDB	you already have code on the AWS SDK	@aws-sdk/client-dynamodb	—
Native API	you want any language, with no SDK	plain HTTP and WebSocket	—

The ported-source surfaces (Convex, Firestore, Cloud Functions) carry a migration guide because you are moving existing source onto Nimbus. The driver surfaces (MongoDB, DynamoDB) and the native API need no migration — you point an existing client at a Nimbus endpoint and keep your code.

Every surface ships runnable examples: Convex, Firestore, Cloud Functions, MongoDB, DynamoDB, and Native API.

Compare what each one supports

Surfaces are not interchangeable: each translates a different slice of the engine. Adapter capabilities puts all six side by side — CRUD, queries, indexes, subscriptions, transactions, schema validation, auth, tenant binding, and default ports — with links into each per-surface reference. The full per-surface compatibility matrices live in the Reference section.

Other wire surfaces

Nimbus serves protocol surfaces that are not app front doors and have no guides in this section: an S3 API (wired by nimbus dev when you declare an AWS S3 client, as above), a Cloudflare-compatible Workers KV plane, and a RESP (Redis) listener started with nimbus kv. Each is documented in the Reference section with its own maturity caveat.