Local-first sync engines

A PouchDB alternative that does not need a CouchDB

IndexedDB in the browser, the same data on another device, and a design that treats offline as normal rather than as an error.

How s3nd works PouchDB

What PouchDB is

In its own terms.

A JavaScript database that runs in the browser, on IndexedDB, and replicates with CouchDB or anything that speaks its replication protocol. Bidirectional, incremental, with conflict detection through revision trees, and around for over a decade.

Side by side

Where they part ways.

	s3nd	PouchDB
What it is	A CLI, a library and React hooks over your own S3 bucket	Browser database with CouchDB replication
Where the data lives	Your bucket: S3, R2, MinIO, Scaleway, Wasabi	A CouchDB server, or a compatible one
Both ends online at once	No. The code is redeemed later, until it expires	No
From inside your web app	Yes, through one route on your server	Yes
Accounts	None. The code is the whole handshake	CouchDB authentication
Hosting	Your bucket, plus your server when a browser takes part	Self-hosted or hosted CouchDB
Price	Free. You pay your storage provider for a few objects that expire	Free
License	MIT	Apache-2.0

The differences

What actually changes.

A database versus a snapshot of yours

PouchDB is the database, with its document model and its revisions. s3nd leaves your database alone, whatever it is, and moves an export of it.

A CouchDB versus a bucket

Replication needs a CouchDB, or a compatible server, running somewhere. s3nd needs object storage and nothing else.

Continuous replication versus a code

PouchDB syncs as long as it is connected. s3nd moves the data once, when the user asks, and the code is the only credential.

The decision

Pick the one that fits.

Pick PouchDB when

You want a database that syncs, with revisions and conflicts as first-class concepts.
A CouchDB you already run, or a hosted one you are happy to rent.
Continuous bidirectional replication is the feature.