Otis

Name: Otis
Author: otisbase

by otisbaseversion 0.1.0i★ –iRuns in the cloud

Registry namecom.otisbase/otis

Install

Overview

Description from the maker (original English)

Free client billing for AI assistants: hours, expenses, timers, invoices and payments.

PopNx MCP’s three pillars

These three are never merged into one score: opinions, measurements and popularity are different things.

User voiceiNo reviews yetReviews open together with accounts in a later step
Our basic checksi3 of 3 passedChecked from public information; code not scanned yet
UsageiVery new★ –

What you can do with it

We have not written a plain-language summary for this one yet. Below are the facts we read from the registry.

Connection: Runs in the cloud
Transport: Streamable HTTP
Category: Accounting, finance & tax

Install

Pick the AI app you use, then copy the settings.

Before you install

Basic checks: 3 of 3 passed
Runs on the maker’s server: what you ask it goes through their server.
The registry lists no key to fill in.

You need

Runs in the cloudNothing to install; it connects over the internet

Which app do you use?

ClaudeClaude CodeCursorVS CodeChatGPT

Pick your app above. We remember it, so next time the button says “Install in …”.

Works in Claude on the web, desktop and mobile:

Open Settings → Connectors
Press Add custom connector
Paste the address below and press Add
If it asks you to sign in, sign in with the maker

https://mcp.otisbase.com/mcp

Run this in your terminal

claude mcp add --transport http otis https://mcp.otisbase.com/mcp

Open in Cursor

Or copy the settings yourself

Paste into .cursor/mcp.json in your project, or ~/.cursor/mcp.json

{
  "mcpServers": {
    "otis": {
      "url": "https://mcp.otisbase.com/mcp"
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

Open in VS Code

Or copy the settings yourself

Paste into .vscode/mcp.json in your project

{
  "servers": {
    "otis": {
      "type": "http",
      "url": "https://mcp.otisbase.com/mcp"
    }
  }
}

Your browser asks to open the app, then the app shows the settings and asks you to confirm. Key values are left empty for you to fill in.

ChatGPT connects only to servers on the internet:

Open ChatGPT on the web → Settings → Connectors (Apps)
Press Create or Add (some plans need Developer mode under Advanced first)
Paste the address below, give it a name and save
If it asks you to sign in, sign in with the maker

https://mcp.otisbase.com/mcp

Menu names can differ slightly by plan and over time.

Your choice stays on this device in a cookie; no account needed.

These settings are generated from the maker’s registry entry. If the README says otherwise, follow the README.

What it can do

The server asks you to sign in before it lists its tools.

Basic checksi

We check information anyone can see; we have not read the code. Checks that do not apply are left out of the count. · Checked Nov 9, 2026

✓ Pass
Maker matches the repo
The registry name was verified against the domain otisbase.com (the registry checks domain ownership)
… Not checked yet
Still maintained
We have not read this repo from GitHub yet
… Not checked yet
Has a licence
We have not read this repo from GitHub yet
✓ Pass
Endpoint responds
Responded in 55 ms (HTTP 401)
✓ Pass
Sign-in with OAuth
Declares OAuth sign-in, so your AI app can take you to log in
… Not checked yet
No hidden instructions in tool descriptions
Not checked yet; we read the tool list when we check the endpoint

Compared with others in Accounting, finance & taxi

More stars than 0% of the other 3036 servers in this category
Published to the registry more recently than 63% of the other 3036 servers in this category
Basic checks equal to or better than 100% of the other 3036 servers in this category

Compared with every active server in this category in the registry. Stars count only when the publisher owns the repo.

Common questions

Is Otis safe?

It passed 3 of 3 applicable basic checks. We have not read the code. Before adding a key or token, see what access the server asks for and use a key with only the permissions you need.

What keys or codes does it need?

The registry does not list a required key, though some servers ask you to sign in on first use.

Does it run on my computer or in the cloud?

It runs in the maker’s cloud. Connect over the internet with nothing to install, but what you send passes through the maker’s servers.

Is it still maintained?

The GitHub repo last changed –, and the latest version (0.1.0) reached the registry 17 days ago.

Which apps can use it?

Apps that support MCP, such as Claude Desktop, Claude Code, Cursor and VS Code. It connects by URL, so apps that accept remote MCP servers work too, such as ChatGPT in developer mode.

What can I use instead?

In the same category: Finance Toolkit, SolidInvoice, Korea Tax Calculator

Alternatives

Servers in the same category from other makers, sorted by stars.

Reading a card:↓ Downloads per weeki★ GitHub starsiThree pillars: reviews · checks · usageiUpdated = latest version published to the registryi

Finance Toolkit

500+ transparent financial methods calculated from raw statements, not third-party endpoints.

by JerBoumaWidely used↓ 15.5K/wk★ 5.5KUpdated today

Computer or cloud

Install

SolidInvoice

Create and send invoices and quotes, manage clients, and track payments in SolidInvoice.

by SolidInvoiceGrowing★ 981Updated today

Runs in the cloud✓ solidinvoice.co

Install

Korea Tax Calculator

Korean tax calculation and tax-audit judgment MCP: 97 tools with statutory citations.

by UpstageAIGrowing↓ 3.2K/wk★ 97Updated today

Runs on your computer

Install

README from the maker

Open the README

Copied from the maker’s repo as written. PopNx MCP has not reviewed or endorsed it. HTML, images and scripts are removed. Links lead off this site.

Otis MCP

The source code of Otisbase, a free MCP server for client billing, built for consultants and small agencies.

Otis has no app or dashboard. Your AI assistant is the interface: it records clients, work, expenses and payments in Otis, and issues the invoices you approve. Otis stores the records and enforces the rules. It numbers invoices, calculates totals, requires your exact total before it issues an invoice, and never rewrites an issued invoice. Otis runs no AI model; every result comes from the records and the rules in this repository.

This repository is the complete service that runs at mcp.otisbase.com: the MCP server, email sign-in and the storage layer. It runs on Cloudflare Workers. The otisbase.com website is maintained separately.

Use the hosted service

Add this URL as a remote MCP server in your assistant:

https://mcp.otisbase.com/mcp

Sign-in uses OAuth with an email code, so there is no API key. How to install has a guide for Claude, ChatGPT, Claude Code, Codex, Cursor, Muse, Grok Bot and Mistral Vibe. The hosted service is free. Records are stored in the EU.

MCP docs: the endpoint, the rules and every tool.
Otis plugins, a menu and nine workflow skills for each assistant: Claude, ChatGPT and Codex, Grok and Cursor and other agents.
Skills: what each skill does.

What Otis records

Area	Records
Business	Business details, tax settings and invoice numbering, used by its owner
Clients	Clients and their billing details
Work	Billable time, services, reported AI usage and expenses
Invoices	Drafts, issued invoices with immutable contents, discounts and tax
Payments	Full and partial payments, with references that prevent duplicates
Export	A complete export of the business records

How it works

Part	Implementation
Runtime	One Cloudflare Worker (`src/index.ts`)
MCP server	`@modelcontextprotocol/server` over Streamable HTTP at `/mcp` (`src/mcp.ts`)
Sign-in	`@cloudflare/workers-oauth-provider` with an email code (`src/auth.ts`)
Business records	SQLite in one Durable Object per business (`src/business-store.ts`)
Accounts and sign-ins	Durable Objects (`src/account-store.ts`, `src/sign-in-store.ts`)
OAuth state	Workers KV
Email	Cloudflare Email Sending, for sign-in codes and security notices
Data location	Durable Objects in the EU jurisdiction (`src/regions.ts`)
Sign-in pages	Server-rendered HTML with its own small stylesheet (`src/html.ts`, `src/shell.ts`)

Every business operation checks the caller's current membership. Amounts are integers in minor units. Writes take a request ID, so a retried call does not record the same fact twice.

Repository layout

Path	Contents
`src/`	Worker, MCP tools, sign-in, storage, billing rules and public docs
`test/`	Integration tests in Cloudflare's local runtime
`scripts/`	Live endpoint checks and the plugin generator

Read the MCP docs before you change behavior. The rules agents follow are in src/docs.ts, src/descriptions.ts and src/workflows.ts, and the tests in test/ show the rules the server enforces.

Develop

You need Node 24 or newer.

npm ci

npm run check npm test

Tests run in Cloudflare's local runtime. Email delivery is simulated in tests.

To run the Worker locally:

npm run dev -- --local --ip 127.0.0.1 --port 8788

Then open http://127.0.0.1:8788/health. The local runtime uses local storage only.

The plugins for each assistant are generated from src/workflows.ts in the private project and published as their own repositories; Skills links them.

Self-host

You can run your own copy on a Cloudflare account. Edit wrangler.jsonc before you deploy:

Set account_id to your Cloudflare account.
Create a KV namespace for OAuth state and put its ID in kv_namespaces. For EU storage, create it in the EU jurisdiction.
Replace the two routes with your own domains.
Set the vars:

ORIGIN: the URL of the MCP host.
SITE_ORIGIN: the URL of your website. Website pages opened on the MCP host redirect there, and the sign-in pages link to its Terms and Privacy Policy.
EMAIL_FROM: the sender for sign-in codes. The domain must be set up for Cloudflare Email Sending.
FEEDBACK_TO: the address that receives feedback sent through the feedback_send tool.
DO_JURISDICTION: eu keeps Durable Objects in the EU. Remove it to let Cloudflare choose.
SIGN_IN_ENABLED: true to allow sign-in.

Set ratelimits.namespace_id to an ID that is unique in your account.

Then deploy:

npx wrangler login

npm run deploy

The sign-in pages and emails name Otisbase. Change them in src/html.ts, src/auth.ts and src/notify.ts, and publish your own terms and privacy policy, before you offer your copy to other people.

Contribute

Bug reports, fixes and ideas are welcome. See CONTRIBUTING.md. To report a security problem, see SECURITY.md. You can also send feedback from your assistant: ask it to send feedback to Otis.

License

The code is released under the MIT License.

These items are not covered by the MIT License:

The Otisbase and Otis names and logos.
The Geist fonts in src/fonts/, under the SIL Open Font License.

The copy and check icons in src/html.ts come from Phosphor Icons (MIT).

Otis

Overview

PopNx MCP’s three pillars

What you can do with it

Install

Before you install

What it can do

Basic checksi

Maker matches the repo

Still maintained

Has a licence

Endpoint responds

Sign-in with OAuth

No hidden instructions in tool descriptions

Compared with others in Accounting, finance & taxi

Common questions

Alternatives

Finance Toolkit

SolidInvoice

Korea Tax Calculator

README from the maker

Otis MCP

Use the hosted service

What Otis records

How it works

Repository layout

Develop

Self-host

Contribute

License