A localstorage alternative for AI coded apps.

No-accounts no-backend database for when full backend is too much, but local storage is not enough. You get: cross-device data, SSO, key/value, lists, maps, file storage, optimistic updates, off-line mode.

Get Started → Read the docs

            
            1 
2<!-- include prefsdb in your project -->
3<script src="https://prefsdb.com/prefsdb.v1.min.js"></script>
4

            5// mint a key from a phrase only your user knows (first run: PrefsDB emails 
6//    a one-time confirmation link - a security measure overridable by site owners)
7 
8const db = await PrefsDB.getkey("my-app", ["email","passwd"], { email });
9 

            10// write a value
11await db.setItem("theme", "dark");
12 
13// read a value, value === "dark" on any browser on any device
14const { value } = await db.getItem("theme");

setValue/getValue
Lists & Maps
File Storage
SSO
Undo & History
Pub/Sub Channels
TTL
Off-line Mode
Optimistic Updates
Client-side encryption

A DIFFERENT CONCEPT - LIKE LOCALSTORAGE BUT BETTER

When a traditional backend is too much but localStorage is not enough

NO SERVERS • NO BACKEND

True serverless "backend"

PrefsDB fills the gap between the convenience of localStorage and backend's flexibility. You get data persisted across devices, secure object storage, offline mode, optimistic updates, key/value, lists, maps, and more.

NO-ACCOUNTS MODEL

No accounts ‐ no sign-ups

Many people feel strong aversion to creating ever more accounts. Many things actually do not warrant an account - but still need to store data. PrefsDB offers a new concept where devs can offer account-like functionality without creating accounts at the backend.

NO LOCALSTORAGE SHORTCOMINGS

Outgrow local storage

Local in-browser storage APIs can be great but they suffer from significant trade-offs:
❌ 5-10MB storage limit,
❌ data loss on device wipe,
❌ no cross-device persistence,
❌ main thread blocking
Prefsdb fixes that. 👉 Learn more...

USER-PAYS MODEL

No cost to devs

✅ PrefsDB is free for developers. Every user of your app gets their own API key, and every key comes with a free allowance of requests and storage.
✅ Your costs don't grow with your user count: whether your app has 1 user or 1 million, it costs you nothing to run. Your users own their data and they decide how to handle it — if at all — all depending on your app's goals. 👉 Learn more.

EXTEND LOCALSTORAGE WITH LISTS, MAPS, OBJECT STORAGE

More than a basic key/value store.

📦

Lists & Maps

Collections like list.add() , map.put() offer flexibility beyond basic key/value storage.

⇪

File storage

File uploads API stores all files encrypted with a embeddable link.

↺

Undo & history

Turn on value history and undo() pops the most recent writes back.

⟲

Pub/sub channels

Publish to a named channel, subscribe from any device — lightweight, poll-based realtime.

⌛

Time-to-live

.ttl(7) expires a key automatically — invite codes, one-time tokens, caches.

🔑

Security

Your users' data is secure with multiple encryption levels: at-rest, in-transit, client-side encryption.

⇄

Off-line mode

Spotty connections, no WI-FI — your users will appreciate working apps even when offline.

⚡

Optimistic updates

Your apps will feel very fast ad responsive with optimistic updates feature.

FOR AGENTS & LLMS

Made for AI

Easy for humans — perfect for LLMs. Plain HTTP query params in, JSON out — no SDK to install and no auth wall beyond a header. A coding agent can go from docs to a working call without guessing.

llms.txt — a machine-readable map of every doc page, built for LLMs and coding agents
Every endpoint's request/response shape and error codes are documented in markdown any AI agent can understand.
prefsdb.v1.js is unminified — a model can read the client source directly instead of guessing at behavior
Tell your AI agent to read https://prefsdb.com/llms.txt to get going.

View llms.txt →

agent.sh

            
              1# keep your agent's state between runs: plain HTTP, no SDK
2# 1. end of a run: save where it left off
3curl -s "https://prefsdb.com/api/v1/write/?last_task" \
4  -H "X-Authorization: Token $PREFSDB_SERVER_KEY" \
5  -H "Content-Type: text/plain" \
6  --data-binary "refactored auth module, tests pass, next: docs"
7 
8# 2. start of the next run, on any machine: pick it back up
9curl -s "https://prefsdb.com/api/v1/read/?last_task" \
10  -H "X-Authorization: Token $PREFSDB_SERVER_KEY"
11# -> { "value": "refactored auth module, tests pass, next: docs", 
11# ->      "count": 1, ... }

            
          

A DATABASE IN THE BROWSER

A faster approach to storing data.

PrefsDB offers a different approach to traditional backend flow. User provided credentials automatically become a unique API token by which all of that user's data is gated. Your write your app as if for a single user. PrefsDB will do all the rest.

Hands-off approach — No setting up accounts for your users, no responsibility for handling their data.
PrefsDB only works with the hashes of the token seed — credentials never leave the client side
User-pays model shifts responsibility to the user.
Files and all data at-rest are encrypted by default.
PrefsDB can be used in GDRP compliant manner.

quickstart.js

              1// three steps: add the script, mint a key, read/write
2const db = await PrefsDB.createkey("my-app", ["s1", "s2"], { email });
3 
4await db.domain("prefs").key("theme").write("dark");
5await db.list("recent-searches").add("tape delay pedals");
6const all = await db.domain("prefs").readAll();

DATABASE IN A BROWSER

Lists, maps, keys and values

Something about how most tasks need those three basic data storage types. They are searchable, redundant, secure - all with no backend.

Secure — all values are stored encrypted at-rest by default.
No vendor lock-in — all data belongs to you or your users. Download all data at any time via dashboard links or via the API.
Offline mode — your users will not loose data just because they lost their Wi-Fi. Your app will continue as if nothing happened.
Delightfully fast — with optimistic updates your app's UI will feel super fast and responsive.
AI Ready — Tell your AI agent to read https://prefsdb.com/llms.txt to get started with PrefsDB.

View llms.txt →

            
            
            
          

            1<!-- add to a list -->
2await db.list("users").add("name");
3
4<!-- get a list -->
5const { names } = await db.list("users").read();
6
7<!-- filtered read from a list -->
8const { names } = await db.list("users").match("%yahoo.com").read();

          

            1<!-- add to a map -->
2await db.map("settings").key("theme").write("dark");
3
4<!-- read a value from a map -->
5const { theme } = await db.map("settings").key("theme").read();
6
7<!-- get the whole map -->
8const { entries } = await db.map("settings").read();

          

            1<!-- set a key value -->
2await db.key("level").write(2);
3
4<!-- read a key value -->
5const { level } = await db.key("level").read();
6
7<!-- read all values -->
8const { value } = await db.project("project-name").readAll();

          

USER OWNED DATA

Data dashboards

Every API key receives a unique dashboard link allowing your users to review their data, search it, create backups, and manage quota limits. It is an optional step - it is up to you to expose this functionality to your users in your app.

View test dashboard →

1
2	<!-- include prefsdb in your project -->
3	<script src="https://prefsdb.com/prefsdb.v1.min.js"></script>
4

5	// mint a key from a phrase only your user knows (first run: PrefsDB emails
6	// a one-time confirmation link - a security measure overridable by site owners)
7
8	const db = await PrefsDB.getkey("my-app", ["email","passwd"], { email });
9

10	// write a value
11	await db.setItem("theme", "dark");
12
13	// read a value, value === "dark" on any browser on any device
14	const { value } = await db.getItem("theme");

1	# keep your agent's state between runs: plain HTTP, no SDK
2	# 1. end of a run: save where it left off
3	curl -s "https://prefsdb.com/api/v1/write/?last_task" \
4	-H "X-Authorization: Token $PREFSDB_SERVER_KEY" \
5	-H "Content-Type: text/plain" \
6	--data-binary "refactored auth module, tests pass, next: docs"
7
8	# 2. start of the next run, on any machine: pick it back up
9	curl -s "https://prefsdb.com/api/v1/read/?last_task" \
10	-H "X-Authorization: Token $PREFSDB_SERVER_KEY"
11	# -> { "value": "refactored auth module, tests pass, next: docs",
11	# -> "count": 1, ... }

1	// three steps: add the script, mint a key, read/write
2	const db = await PrefsDB.createkey("my-app", ["s1", "s2"], { email });
3
4	await db.domain("prefs").key("theme").write("dark");
5	await db.list("recent-searches").add("tape delay pedals");
6	const all = await db.domain("prefs").readAll();

1	<!-- add to a list -->
2	await db.list("users").add("name");
3
4	<!-- get a list -->
5	const { names } = await db.list("users").read();
6
7	<!-- filtered read from a list -->
8	const { names } = await db.list("users").match("%yahoo.com").read();

1	<!-- add to a map -->
2	await db.map("settings").key("theme").write("dark");
3
4	<!-- read a value from a map -->
5	const { theme } = await db.map("settings").key("theme").read();
6
7	<!-- get the whole map -->
8	const { entries } = await db.map("settings").read();

1	<!-- set a key value -->
2	await db.key("level").write(2);
3
4	<!-- read a key value -->
5	const { level } = await db.key("level").read();
6
7	<!-- read all values -->
8	const { value } = await db.project("project-name").readAll();