Zero

Zero, Sync engine that puts a queryable client cache in front of your own Postgres. Zero is Rocicorp's general-purpose sync engine, the successor to Replicache. Your Postgres stays the source of truth; zero-cache replicates from it and serves ZQL queries to clients out of a local store, so reads are instant and writes go through custom mutators that run server-side in a real transaction. It brings no auth, storage or cron, it does one thing and leaves the rest of your stack alone. Built by Rocicorp. Founded 2019. Venture-backed. Open source.

We track it in 1 comparison, Convex alternatives, so every claim below is a cell in a table you can open and check rather than an impression. Across those rosters it sits against 10 other tools, and what follows is where it visibly separates from them.

Where it wins.

• Local-first sync, Yes, which only 3 of 11 tools here manage.
• Entry price, $0 /mo, tied for best across 3 of 9 tools.

Each of those is ranked against the whole roster on its category page, not against a hand-picked subset, so a first place here means first of everything we list.

Where it gives ground.

• Auth, bring-your-own, 8th of 11. Supabase records built-in.
• MCP server, No. Convex records Yes.
• File storage, No. Convex records Yes.
• Egress metered, No. Convex records Yes.

None of these disqualify it on their own. They are the fields to check against your own requirements before you commit, because they are the ones where a competitor genuinely does better.

Provenance. 24 of 26 tracked fields carry a value for Zero, and 7 of those cite a document you can open. Last verified 2026-07-20. Every figure keeps its own provenance, measured by us, claimed by the vendor, inferred, or community-reported, and we would rather print a dash than a guess.

Its nearest neighbour in our data is Appwrite. Zero is ahead on Transactions (mvcc against none) and Local-first sync (Yes against No). Appwrite takes Cron & scheduling (Yes against No) and Auth (built-in against bring-your-own). That pattern repeats across the rest of the roster, see Zero alternatives for the other rivals, each compared the same way.

Company

Rocicorp

Founded

2019

Funding

Venture-backed

Licence

Open source

Fields we track

24 of 26

Last verified

2026-07-20

The most interesting shape on this page: instant local reads without surrendering the database. You still operate zero-cache and Postgres yourself, and you get no auth, storage or cron, this is a layer, not a platform.

Local-first sync

●Yes1st of 11

Vendor-claimedverified 2026-07-20source

Entry price

$0 /mo1st of 9

Inferred

Auth

bring-your-own8th of 11

Vendor-claimedverified 2026-07-20source

MCP server

○No8th of 11

Inferred

File storage

○No8th of 11

Inferred

Egress metered

○No8th of 9

Inferred

GitHub stars

3,00010th of 10

Inferred

Reactivity

push1st of 11

Vendor-claimedverified 2026-07-20source

Zero is the right call in these situations, each one drawn from a field we actually record:

• Teams with an existing Postgres who want a UI that feels local.
• Apps where snappy reads matter but ownership of the data model is non-negotiable.
• Adding sync incrementally rather than rewriting onto a backend platform.
• Local-first sync is your binding constraint. Zero records Yes, which only 3 of the 11 tools in the Convex alternatives roster do. We define that field as whether the client keeps a queryable local store that serves reads offline and reconciles with the server on reconnect.
• Entry price is your binding constraint. Zero records $0 /mo, the best figure in the Convex alternatives roster. We define that field as monthly cost of the cheapest paid tier, excluding usage, in USD.

Reach for something else when any of the following is a requirement rather than a nice-to-have:

• Auth. Zero records bring-your-own, 8th of 11 in the Convex alternatives roster. Supabase records built-in on the same field. If that is a hard requirement rather than a preference, start elsewhere.
• MCP server. Zero records No on the Convex alternatives table. Convex records Yes on the same field. If that is a hard requirement rather than a preference, start elsewhere.
• File storage. Zero records No on the Convex alternatives table. Convex records Yes on the same field. If that is a hard requirement rather than a preference, start elsewhere.
• Egress metered. Zero records No on the Convex alternatives table. Convex records Yes on the same field. If that is a hard requirement rather than a preference, start elsewhere.
• GitHub stars. Zero records 3,000, the weakest of the 10 tools in the Convex alternatives roster. Supabase records 90,000 on the same field. If that is a hard requirement rather than a preference, start elsewhere.

We publish this block because a comparison that only lists what a tool is good at is marketing. Every figure above sits on the same page as its source, and the field definitions are on the category tables if you want to check how we measured them.

What we don't know. 2 of the 26 fields we track for Zero are still blank: Cold start and Function timeout. Those render as dashes rather than as zeroes or assumptions, because an empty cell and a bad cell are not the same thing and only one of them is honest. If you know any of these figures and can point at a document, tell us.