A compact KOSync backend written in TypeScript for KOReader. Runs on Deno + Hono and can be deployed 100% free using Deno Deploy + Supabase (free).

• Runtime/server: Deno + Hono
• Validation/OpenAPI: zod + @hono/zod-openapi
• Storage: KV abstraction with multiple drivers (SQLite, Deno KV, Supabase, Redis, Postgres, MongoDB, DuckDB)
• API base path: /v1

• User sign-up with username/password stored in a KV store
• Lightweight auth via x-auth-user and x-auth-key headers
• Persist reading progress per document and retrieve the latest record
• Healthcheck endpoint

1. Register Supabase
2. Create project Supabase
3. Create table kv_store (or table name your set in env TABLE_NAME) with key is TEXT and UNIQUE, value is TEXT
4. Get SUPABASE_URL and SUPABASE_KEY
5. Deploy to Deno Deploy
6. Set env get from 4) to settings project
7. Add your server to Kindle with url <base url>/v1. Example: https://kosync-typescript.tachibana-shin.deno.net/v1
8. Enjoy

Tip

If you see this in log Deno

Make sure you have turned off the RLS of the kv_store

In addition, you can use my server has been deployed at https: //kosync-typescript.tachibana-shin.deno.net/v1 but I do not guarantee your data always online

• main.ts: bootstraps Hono app, middleware, routes, and Deno.serve
• constants.ts: constants, error codes and raiseError helper
• middleware/authorize.ts: reads headers, validates against KV, attaches user to context
• logic/valid.ts: simple input validators
• kv/: KV abstraction (KvBase) and drivers
  • kv/index.ts: selects the KV driver used at runtime
  • kv/drivers/*: KV drivers (sqlite, deno-kv, supabase, redis, postgres, mongodb, duckdb)
• v1/: API routes
  • healthcheck.ts
  • users/
    • auth.get.ts
    • create.post.ts
  • syncs/progress/
    • index.put.ts
    • [document].get.ts
• deno.json: tasks and import map
• main_test.ts: integration tests (expects server running)

Requirements: Deno v1.41+ (npm compatibility enabled).

By default the project uses the SQLite driver (see kv/index.ts) in test. You can:

• Keep SQLite for local development, or
• Switch to Deno KV for a zero-setup local store

Start the server:

• Dev (watch): deno task dev
• Local prod-like: deno task start

The server listens on http://localhost:8000 and exposes the API under /v1.

Notes about KV drivers locally:

• SQLite (default): a sqlite.db file is created in the project directory.
• Deno KV: switch to DenoKv in kv/index.ts if you prefer no SQLite dependency (see "Choose a KV driver").

Base URL: http://localhost:8000/v1 (or your Deno Deploy URL + /v1)

1. Healthcheck

• GET /healthcheck
• Response: 200 { "state": "OK" }

2. Create user

• POST /users/create
• JSON body: { "username": string(min 3), "password": string(min 6) }
• Response: 201 { "username": "..." }
• Errors:
  • 402 { "code": 2002, "message": "Username is already registered." }
  • 403 { "code": 2003, "message": "Invalid request" }

Example:

curl -X POST http://localhost:8000/v1/users/create \
  -H "Content-Type: application/json" \
  -d '{"username":"alice","password":"secret123"}'

3. Check authorization

• GET /users/auth
• Required headers:
  • x-auth-user: username
  • x-auth-key: password used at sign-up
• Responses:
  • 200 { "authorized": "OK" }
  • 401 { "code": 2001, "message": "Unauthorized" }

Example:

curl -X GET http://localhost:8000/v1/users/auth \
  -H "x-auth-user: alice" \
  -H "x-auth-key: secret123"

4. Update reading progress

• PUT /syncs/progress
• Required headers: x-auth-user, x-auth-key
• JSON body:

  {
    "document": "string (min 3)",
    "percentage": 0-100,
    "progress": "string",
    "device": "string",
    "device_id": "string (optional)"
  }

• Response: 200 { "document": "...", "timestamp": number }
• Errors: 401 Unauthorized, 403 Invalid fields, 500 Internal

Example:

curl -X PUT http://localhost:8000/v1/syncs/progress \
  -H "Content-Type: application/json" \
  -H "x-auth-user: alice" \
  -H "x-auth-key: secret123" \
  -d '{
        "document": "book_1984",
        "percentage": 42,
        "progress": "page_124",
        "device": "KOReader"
      }'

5. Get reading progress by document

• GET /syncs/progress/{document}
• Required headers: x-auth-user, x-auth-key
• Success responses:
  • 200 {} (if no data)
  • 200 { document, percentage?, progress?, device?, device_id?, timestamp? }

Example:

curl -X GET http://localhost:8000/v1/syncs/progress/book_1984 \
  -H "x-auth-user: alice" \
  -H "x-auth-key: secret123"

Default: kv/index.ts uses SQLite. You can switch to any of the provided drivers depending on your environment:

• Deno KV (zero config; great for local or Deno Deploy with KV enabled)
• Supabase (ideal for free deployment with Deno Deploy + Supabase)
• Redis, Postgres, MongoDB, DuckDB (require extra setup/services)

How to switch:

• Open kv/index.ts and replace the kv initialization with the desired driver.
• Supabase example:
  • Set env vars SUPABASE_URL and SUPABASE_KEY
  • Create table kv_store on your Supabase Postgres (see below)
  • Use the SupabaseKv driver

Example (illustrative):

import { SupabaseKv } from "./drivers/supabase-kv.ts"
export const kv = new SupabaseKv()

Deno KV example:

import { DenoKv } from "./drivers/deno-kv.ts"
export const kv = new DenoKv()

Make sure await kv.init() is called before serving requests (already done in main.ts).

Goal: run the app on Deno Deploy and store data in Supabase (free tier).

Step 1: Prepare Supabase (free tier)

• Create a project at https://supabase.com/ (free tier)
• Obtain the following:
  • SUPABASE_URL: Project URL
  • SUPABASE_KEY: Service role key or anon key. For server-only access, service role key is recommended.
• Create the kv_store table in your Database via SQL Editor:

create table if not exists kv_store (
  key text primary key,
  value jsonb
);

Notes:

• If Row Level Security (RLS) is enabled, using the Service Role key allows unrestricted access from server-side. Do not expose it to the client.

Step 2: Switch the KV driver to Supabase

• Edit kv/index.ts and use SupabaseKv as shown above.

Step 3: Push source to GitHub

• Push this repository to your own GitHub account

Step 4: Create a project on Deno Deploy

• Go to https://dash.deno.com/ → New Project → Link your GitHub repo
• Select main.ts as the entrypoint
• Set Environment Variables:
  • SUPABASE_URL = your Supabase project URL
  • SUPABASE_KEY = your Supabase service role key (recommended)
• Deploy

Step 5: Verify

• Healthcheck: https://<your-app>.deno.dev/v1/healthcheck
• Create user, auth, update/get progress as in the API section

Security considerations:

• This demo stores passwords in plain text in KV. For real use, hash passwords (e.g., bcrypt/argon2) before storing.
• Consider rate limiting, stricter auth, and CORS rules for production.

• Server base URL: https://<your-app>.deno.dev/v1
• Create an account via /users/create
• Client must send headers:
  • x-auth-user: username
  • x-auth-key: password
• Update progress via PUT /syncs/progress with the schema above.

Depending on KOReader version/config, you may need a plugin or custom configuration to send custom headers.

Integration tests live in main_test.ts and exercise the HTTP API.

• Terminal A: start the local server
  • deno task start
• Terminal B: run tests with full permissions (HTTP calls to localhost)
  • deno test -A main_test.ts

With the SQLite driver, tests operate on sqlite.db in the repo directory.

See the LICENSE file for details.