The free back office for your software business - that you actually own
Recurring invoices, customers and real double-entry books, behind a full REST API you can automate - free, self-hosted, and yours. No per-seat fees, no vendor lock-in.
Source-available, with open-source modules. Runs on your own machine. Full REST API (OpenAPI 3.1).
Quick answers
Is Celerp free?
Yes. The desktop app is free for business use: no account needed, no per-user fee and no limits on companies, users, items or records. The core is source-available and the modules are MIT-licensed.
Does it work offline, and can I self-host it?
Yes. Celerp runs on your own computer and works offline: the core product needs no internet connection. You can also self-host it on an office or cloud server, so the database stays on hardware you control.
What does Celerp cover?
Inventory, invoicing, purchasing, full accounting, CRM, manufacturing with bills of materials, and reporting, all sharing one set of data.
Which industries is it built for?
It ships with presets for retail, jewelry, gemstones, watches, coins, fashion, cosmetics, food and beverage, wine and spirits, agriculture, electronics, auto parts, hardware, furniture, books and media, art and consulting.
What does Celerp Connect cost?
$29 a month or $290 a year for your whole setup, never per user, with the first 14 days free before billing starts. Connect adds store and accounting sync, remote access, 100 included AI queries and encrypted cloud backups. The desktop app works fully without it.
Updated for version 2.9.0 on .
Why software founders run Celerp
Your billing and books shouldn't be a stack of subscriptions you don't control - or a database you can't query.
Who's about to renew - and who's already overdue?
The subscriptions module tracks every plan's recurring invoice, and the invoice list shows what's overdue, so you're not digging through five tools to find out.
Billing software you don't own
Run it on your own machine or server. The records are yours - no vendor database you can only query through their dashboard.
Customers and revenue in one place
Track who pays what and what's outstanding, with real double-entry books behind it - not spreadsheets next to a billing tool.
Automate the boring parts
Every action in Celerp is a REST endpoint (OpenAPI 3.1) - wire invoicing and customer records straight into your own app.
Celerp is the layer you own - not a payment processor. It keeps your billing records and books. Card payments go out as a Celerp Connect pay link and land in your own Stripe account; Connect keeps 1% of each online payment. Think of it as the self-hosted billing and accounting layer behind your software business, one you can automate end to end.
Up and running in minutes
Install free
Download the desktop app, or pip install celerp on a server. One command, no account, no credit card.
Set up plans & customers
Add your customers and recurring invoices for your plans and seats - or create them straight from your app via the API.
Automate with the REST API
Every action is an endpoint. Create invoices, read revenue, post entries - wire Celerp into your product and scripts.
Built for builders
A back office that behaves like infrastructure you control.
OpenAPI 3.1 - every UI action is also an endpoint. The same API the app uses.
Recurring invoices on any cadence, weekly to annual or custom, billed in advance or in arrears. Bill each due period by hand, or turn on automatic billing and Celerp creates the invoice on schedule while it's running, and can email it too. Pause, resume or cancel anytime.
Real double-entry books in any currency, always in balance.
Runs on your machine or server. Your data stays there unless you turn on Connect.
Want it to sync to QuickBooks/Xero, run from anywhere, or back up off-site? That's Celerp Connect ($29/mo). The API and self-hosting are free.
Why Celerp fits a software business
The back office of an ERP, with the manners of a dev tool.
- ✓ Free forever - the whole app, no account needed
- ✓ Full REST API (OpenAPI 3.1)
- ✓ Recurring invoices for plans & seats
- ✓ An overdue list, so you always know who hasn't paid
- ✓ Real double-entry accounting
- ✓ Invoices with several lines, each to its own income account
- ✓ Multi-currency
- ✓ Self-hosted - desktop or your own server
- ✓ Source-available, no vendor lock-in
- ✓ Add your whole team - no per-user fee
- ✓ Pay links through your own Stripe account, brokered by Celerp Connect
- ✓ Pause, resume or cancel a subscription anytime, or stop it at the end of the current period
For your accountant
The numbers your bookkeeper needs to close the books, not just a revenue figure.
If a customer pays a year upfront, that's deferred revenue until it's earned - your accountant will want it recognized month by month, not booked as income the day it lands.
Every invoice and payment in Celerp posts to real double-entry books: a general ledger and trial balance your accountant can open directly, with journal entries they can adjust by hand for a plan that needs its revenue spread across the term.
See what your accountant sees
Free to start. Cheap to grow.
The whole app - and the full API - are free. Add Connect only when you want sync, remote access or backups.
The complete app and the full REST API - recurring invoicing, customers and accounting. No account needed, no per-user fee.
- ✓ Full REST API (OpenAPI 3.1)
- ✓ Recurring invoicing & accounting
- ✓ Self-hosted - desktop or server
- ✓ Your data stays yours
Sync to your accountant's tools, reach it from anywhere, and back it up.
- ✓ Everything in Free
- ✓ Sync to QuickBooks & Xero
- ✓ Use it from any device, anywhere
- ✓ Automatic encrypted backups
- ✓ AI helper for the boring stuff
Free for the first 14 days. Cancel anytime.
Questions software founders ask
Is it really free?
Yes - the whole app, including the full REST API, recurring invoicing and accounting, is free forever with no per-user fee. Optional Connect features (accounting sync, remote access, AI, backups) are a low monthly add-on.
Does it charge my customers' cards?
Celerp is not a payment processor. Connect your own Stripe account and each invoice gets a Celerp Connect pay link your customer can pay by card. The money goes straight into your Stripe account.
How good is the API?
Every action in the app is a REST endpoint, documented as OpenAPI 3.1 - the same API the UI uses. Each app release on GitHub has its openapi.json attached, and the API reference on this site is built from it: download the file and generate a typed client in your language.
Can I self-host and own my data?
Yes. Run it on your own machine or server; your data stays there unless you turn on Connect sync or backups. It's source-available with no vendor lock-in.
Can it do recurring billing?
Yes. Give each customer's plan a subscription on any cadence, weekly to annual or custom, billed in advance or in arrears. Bill each due period by hand, or turn on automatic billing: Celerp creates the invoice on schedule while it's running and, if you choose, emails it. A summary shows what automatic billing created and sent, and anything to check. Celerp never charges a card on its own: customers pay by bank transfer or through a Celerp Connect pay link.
Own your back office
Download Celerp, or read the API guide and wire it into your stack.
Free forever. No account, no credit card.