@vennbase/core

Vennbase

Build multi-user apps without writing a single access rule.

Vennbase is a TypeScript client-side database for collaborative, local-first web apps — with no backend to run, no server to pay for, and no access control rules to misconfigure. Users sign in with their Puter account. Your app only sees the user's subset of the data stored in Puter.

// Write
const board = db.create("boards", { title: "Launch checklist" }).value;
db.create("cards", { text: "Ship it", done: false, createdAt: Date.now() }, { in: board });

// Read (React)
const { rows: cards } = useQuery(db, "cards", {
  in: board,
  index: "byCreatedAt",
  order: "asc",
});

// Share
const { shareLink } = useShareLink(db, board);

Write your frontend. Vennbase handles the rest.

• Zero backend — no server to run, no infrastructure bill
• No access rules to write — share a link, they're in; that's the whole model
• Optimistic updates — instant writes built-in
• Local-first support — app data syncs via CRDT automatically
• NoSQL, open source
• Auth, server functions — via Puter, one login for your whole app
• User-pays AI — Puter's AI APIs are billed to the user, not you; build AI features with zero hosting cost
• Agent-friendly — the explicit-grant model is simple enough that AI coding agents get it right first time

How it works

Every piece of data in Vennbase is a row. A row belongs to a collection defined in your schema, holds typed fields, and has its own identity.

Rows can be nested. A card lives inside a board; a recentBoard lives inside the built-in user collection. The parent relationship defines visibility — gaining access to a parent automatically grants access to its children.

Access is explicit-grant only. To let someone into a row, generate a share link and send it to them. They accept it, they're in. There are no rule expressions to write and no policy surface to misconfigure.

Install

pnpm add @vennbase/core

React apps: pnpm add @vennbase/react @vennbase/core.

Schema

Define your collections once. TypeScript infers field types throughout the SDK automatically.

import { collection, defineSchema, field, index } from "@vennbase/core";

export const schema = defineSchema({
  boards: collection({
    fields: {
      title: field.string(),
    },
  }),
  recentBoards: collection({
    in: ["user"],
    fields: {
      boardRef: field.ref("boards"),
      openedAt: field.number(),
    },
    indexes: {
      byBoardRef: index("boardRef"),
      byOpenedAt: index("openedAt"),
    },
  }),
  cards: collection({
    in: ["boards"],
    fields: {
      text: field.string(),
      done: field.boolean(),
      createdAt: field.number(),
    },
    indexes: {
      byCreatedAt: index("createdAt"),
    },
  }),
});

export type Schema = typeof schema;

• collection({ in: [...] }) — in lists the allowed parent collections.
• field.string() / .number() / .boolean() / .date() / .ref(collection) — typed fields; chain .optional() or .default(value) as needed
• index(fieldName) — makes a field queryable with ordering and range filters

Fields are for metadata that you want to query or index. The canonical CRDT pattern is: row fields hold metadata and row refs, while the CRDT document holds the collaborative value state for that row.

Setup

Create one Vennbase instance for your app and pass it an appBaseUrl so that share links point back to your app:

import { Vennbase } from "@vennbase/core";
import { schema } from "./schema";

export const db = new Vennbase({ schema, appBaseUrl: window.location.origin });

Auth and startup

import { useSession } from "@vennbase/react";

function AppShell() {
  const session = useSession(db);

  if (session.status === "loading") {
    return <p>Checking session…</p>;
  }

  if (!session.session?.signedIn) {
    return <button onClick={() => void session.signIn()}>Log in with Puter</button>;
  }

  return <App />;
}

Creating rows

// Create a top-level row
const board = db.create("boards", { title: "Launch checklist" }).value;

// Create a child row — pass the parent row or row ref
db.create("cards", { text: "Write README", done: false, createdAt: Date.now() }, { in: board });
db.create("cards", { text: "Publish to npm", done: false, createdAt: Date.now() }, { in: board });

create and update are synchronous optimistic writes. Use .value on the returned receipt when you want the row handle immediately.

To update fields on an existing row:

db.update("cards", card, { done: true });

Querying

Vennbase queries always run within a known scope. For cards, that scope is a board, so you pass in: board. For collections declared as in: ["user"], omitting in means "use the current signed-in user's built-in user row."

Queries never mean "all accessible rows". If a collection is not declared as in: ["user"], omitting in is an error.

Imperative

// `recentBoards` is declared as `in: ["user"]`, so the current user scope is implicit.
const recentBoards = await db.query("recentBoards", {
  index: "byOpenedAt",
  order: "desc",
  limit: 10,
});

// Multi-parent queries run in parallel, then merge and sort their results
const cards = await db.query("cards", {
  in: [todoBoard, bugsBoard],
  index: "byCreatedAt",
  order: "asc",
  limit: 20,
});

With React

@vennbase/react ships a useQuery hook that polls for changes and re-renders automatically:

import { useQuery } from "@vennbase/react";

const { rows: cards } = useQuery(db, "cards", {
  in: board,
  index: "byCreatedAt",
  order: "asc",
});

rows is always a typed array — never undefined.

Sharing rows with share links

Access to a row is always explicit. There is no rule system to misconfigure — no typo in a policy expression that accidentally exposes everything. A user either holds a valid invite token or they don't.

In React, prefer useShareLink(db, row) for the sender and useAcceptInviteFromUrl(db, ...) for the recipient. Underneath, the flow is three steps:

// 1. Generate a token for the row you want to share
const token = db.createInviteToken(board).value;

// 2. Build a link the recipient can open in their browser
const link = db.createShareLink(board, token.token);
// → "https://yourapp.com/?db=..."

// 3. Recipient opens the link; your app calls acceptInvite
const sharedBoard = await db.acceptInvite(link);

acceptInvite accepts either a full invite URL or a pre-parsed { ref, inviteToken? } object from db.parseInvite(input). In React, useAcceptInviteFromUrl(db, ...) handles the common invite-landing flow for you.

Users who join through an invite token are added as direct "editor" members by default. "viewer" members can view rows but cannot call update() or send CRDT messages.

Membership

Once users have joined a row you can inspect and manage the member list:

// Flat list of usernames
const members = await db.listMembers(board);

// With roles
const detailed = await db.listDirectMembers(board);
// → [{ username: "alice", role: "editor" }, ...]

// Add or remove manually
await db.addMember(board, "bob", "editor").committed;
await db.removeMember(board, "eve").committed;

Membership inherited through a parent row is visible via listEffectiveMembers.

Real-time sync (CRDT)

Vennbase includes a CRDT message bridge. Connect any CRDT library to a row and all members receive each other's updates in real time.

Sending CRDT updates requires "editor" access, but all members can poll and receive them.

In React, here is the recommended Yjs integration:

import * as Y from "yjs";
import { createYjsAdapter } from "@vennbase/yjs";
import { useCrdt } from "@vennbase/react";

const adapter = createYjsAdapter(Y);
const { value: doc, flush } = useCrdt(board, adapter);

// Write to doc normally, then push immediately when needed
await flush();

@vennbase/yjs uses your app's yjs instance instead of bundling its own runtime, which avoids the multi-runtime Yjs failure mode.

Example apps

packages/todo-app is the code from this README assembled into a working app — boards, recent boards, cards, and share links. Run it with:

pnpm --filter todo-app dev

For a fuller picture of how the pieces fit together in a real app, read packages/woof-app. It uses CRDT-backed live chat, user-scoped history rows for room restore, child rows with per-user metadata, and role-aware UI — the patterns you'll reach for once basic reads and writes are working.

pnpm --filter woof-app dev

API reference

Vennbase

Method	Description
new Vennbase({ schema, appBaseUrl? })	Create a Vennbase instance. Pass appBaseUrl so share links point back to your app.
getSession()	Check whether the current browser already has a Puter session.
signIn()	Start the Puter sign-in flow. Call this from a user gesture such as a button click.
ensureReady()	Explicitly await authentication and provisioning before mutations. Most useful in imperative startup flows and before imperative writes.
whoAmI()	Returns { username } for the signed-in Puter user.
create(collection, fields, options?)	Create a row optimistically and return a MutationReceipt<RowHandle> immediately. Pass { in: parent } for child rows, where parent can be a RowHandle or RowRef; for collections declared as in: ["user"], omitting in uses the current signed-in user's built-in user row. Most apps use .value; await .committed when you need remote confirmation.
update(collection, row, fields)	Merge field updates onto a row optimistically and return a MutationReceipt<RowHandle> immediately. row can be a RowHandle or RowRef.
getRow(row)	Fetch a row by typed reference.
query(collection, options)	Load rows under a parent, with optional index, order, and limit. For collections declared as in: ["user"], omitting in uses the current signed-in user's built-in user row.
watchQuery(collection, options, callbacks)	Subscribe to repeated query refreshes via callbacks.onChange. For collections declared as in: ["user"], omitting in uses the current signed-in user's built-in user row. Returns a handle with .disconnect().
createInviteToken(row)	Generate a new invite token for a row and return a MutationReceipt<InviteToken>. Most apps can use .value immediately.
getExistingInviteToken(row)	Return the existing token if one exists, or null.
createShareLink(row, token)	Build a shareable URL containing a serialized row ref and token.
parseInvite(input)	Parse an invite URL into { ref, inviteToken? }.
acceptInvite(input)	Join a row via invite URL or parsed invite object, and return its handle. Invite joins become direct "editor" members by default.
saveRow(key, row)	Persist one current row for the signed-in user under your app-defined key.
openSavedRow(key)	Re-open the saved row for the signed-in user, or null.
clearSavedRow(key)	Remove the saved row for the signed-in user.
listMembers(row)	Returns string[] of all member usernames.
listDirectMembers(row)	Returns { username, role }[] for direct members.
listEffectiveMembers(row)	Returns resolved membership including grants inherited from parents.
addMember(row, username, role)	Grant a user access and return a MutationReceipt<void>. Roles: "editor" and "viewer". "editor" can update fields, manage members, manage parents, and send CRDT messages; "viewer" is read-only.
removeMember(row, username)	Revoke a user's access and return a MutationReceipt<void>.
addParent(child, parent)	Link a row to an additional parent after creation and return a MutationReceipt<void>.
removeParent(child, parent)	Unlink a row from a parent and return a MutationReceipt<void>.
listParents(child)	Returns all parent references for a row.
connectCrdt(row, callbacks)	Bridge a CRDT onto the row's message stream. Returns a CrdtConnection.

RowHandle

Member	Description
.fields	Current field snapshot, typed from your schema. Treat it as read-only; the object is replaced when fields change.
.collection	The collection this row belongs to.
.ref	Portable RowRef object for persistence, invites, ref-typed fields, and reopening the row later.
.id / .owner	Row identity metadata.
.refresh()	Re-fetch fields from the server. Resolves to the latest field snapshot.
.connectCrdt(callbacks)	Shorthand for db.connectCrdt(row, callbacks).
.in.add(parent) / .in.remove(parent) / .in.list()	Manage parent links.
.members.add(username, { role }) / .members.remove(username) / .members.list()	Manage membership.

MutationReceipt<T>

Member	Description
.value	The optimistic value available immediately. For create and update, this is the RowHandle.
.committed	Promise that resolves to the final value once the write is confirmed remotely. Rejects if the write fails.
.status	Current write status: "pending", "committed", or "failed".
.error	The rejection reason after a failed write. Otherwise undefined.