For developers

Invoicing built for software developers

REST API, MCP server, OpenAPI 3.1 spec, and a UI for the parts you would rather not script. Send a clean, branded invoice with a tax ID, wire details, and a PO number field your client's AP can fill in directly. Free, no per-invoice fees.

Send your first invoice Read the API docs →

Why developers end up writing their own invoicing tool (and shouldn't)

At some point every freelance developer thinks about building their own invoicing app. It is a satisfying weekend project that turns into a six-month nights-and-weekends commitment that ships a bad version of what already exists.

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You do not want to maintain your own PDF renderer

WeasyPrint, Puppeteer, headless Chrome, font fallback bugs, RTL bugs, page-break bugs. Pay someone else to do this. We do.

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Invoice numbering is harder than it looks

Sequential, gap-free, year-prefixed, locked across clients but unique per sender. JupiterInvoice handles all of this and gives you a free <a href="/tools/invoice-number-generator/">invoice number generator</a> if you want to roll your own.

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Compliance creep eats your weekend

VAT on EU invoices, tax IDs on US invoices, IBAN format validation, currency conversion at the right rate. Each one is a Saturday. Compounded across the year, it is a side project.

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Your client's AP team is the user, not you

Even if you ship the perfect personal invoicing CLI, your client's AP team needs a real link, a PO number field, and a way to forward to finance. They do not run your CLI.

What developers use JupiterInvoice for

REST API and MCP server

Full API with bearer-token auth, OpenAPI 3.1 spec, and an MCP server at /mcp. Drive invoicing from your CRM, your CI, or an LLM agent.

Learn more →

Outbound webhooks

HMAC-signed events on invoice.created, invoice.sent, invoice.viewed, invoice.edited, invoice.forwarded. Pipe into Slack, your CRM, or a custom dashboard.

Quotes and recipient editing

Send a quote that becomes an invoice when accepted. Recipients (your client's PM, AP, finance) can edit billing fields directly without accounts.

Learn more →

A developer-friendly invoicing stack

If you are the kind of developer who prefers reading docs to filling forms, JupiterInvoice is built for you:

  • •API key auth: bearer tokens, scoped per sender profile, rotatable.
  • •OpenAPI 3.1 spec at /api/openapi.json with a Swagger UI at /api/docs/.
  • •MCP server at /mcp using the Streamable HTTP transport (spec 2025-06-18). Claude Desktop and Cursor work out of the box.
  • •Webhook signing follows the Stripe pattern (HMAC-SHA256, signed timestamps), so any existing webhook receiver can be adapted in minutes.

Developer FAQ

What is the best invoicing software for freelance software developers?
The best invoicing tool for developers has a real API, ships an OpenAPI spec, supports webhooks, and does not nickel-and-dime per invoice. JupiterInvoice has all four, and it is free for unlimited invoices. The paid tier (12 dollars a month) just removes the small footer.
Does JupiterInvoice have an API?
Yes. Full REST API with bearer-token auth, JSON in / JSON out, and an OpenAPI 3.1 spec. You can create invoices, customers, sender profiles, and webhook subscriptions programmatically. Docs at <a href="/api/">/api/</a>.
Can I use JupiterInvoice from an LLM agent or MCP client?
Yes. We run an MCP server at /mcp using the Streamable HTTP transport (spec 2025-06-18). Add it to Claude Desktop, Cursor, or any MCP-capable client with an HTTP transport config and an Authorization header. Tools include create_invoice, list_invoices, get_invoice, update_invoice, create_customer, list_customers, get_customer.
Are there outbound webhooks?
Yes. Subscribe via POST /api/v1/webhooks. Events include invoice.created, invoice.sent, invoice.viewed, invoice.edited, invoice.forwarded. Payloads are HMAC-SHA256 signed ("JupiterInvoice-Signature: t=&lt;ts&gt;,v1=&lt;hex&gt;" over &lt;ts&gt;.&lt;raw_body&gt;), the same pattern Stripe uses, so existing receivers adapt easily.
What is the rate limit on the API?
The default rate limit is generous for normal individual use (well above what most developers will hit in a day). If you have a use case that needs higher limits, message us through the contact page and we will raise the cap.
Can I generate invoice PDFs programmatically?
Yes. Every invoice has a PDF endpoint that returns the same WeasyPrint-rendered PDF the recipient sees. Hit /api/v1/invoices/{id}/pdf with a bearer token and you get the file.
Can I self-host JupiterInvoice?
Not at the moment. JupiterInvoice is a hosted product. The whole stack is described publicly (Flask, Postgres, Supabase Auth, Postmark, WeasyPrint), and the API is your escape hatch if you outgrow the hosted UI.
How do I bill in multiple currencies?
Pick the invoice currency on creation. Each sender profile carries its own bank details for USD ACH, EUR IBAN, GBP sort code, plus SWIFT for the rest. Use our free <a href="/tools/currency-converter/">currency converter</a> if you need to quote at today's rate or at a historical rate.
Is there a CLI?
No first-party CLI yet. Most developers use the API directly via curl or HTTPie, or wrap it in a small script for their own workflow. We may ship a CLI if there is enough demand; tell us at the contact page.

Send your first invoice (or POST your first /api/v1/invoices)

Free, unlimited, no per-invoice fees. Bearer-token API auth, OpenAPI spec, MCP server, webhooks. The whole thing.

Create your first invoice

No signup required. Build now, save later.

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