Integrate once.
Issue everywhere.
An API and SDK for Brazilian fiscal documents — real transmission to the tax authorities, manual tax passthrough, and a dashboard to track every submission.
No credit card — free homologation environment.
| Document | Recipient | Amount | Status |
|---|---|---|---|
| NFE · a1b2c3d4 | Comprador Teste Ltda | R$ 2.622,82 | Authorized |
| NFSE · f9e8d7c6 | John Doe | R$ 10.500,00 | Rejected |
| NFE · 5b6a4c3d | Buyer Company Ltd | R$ 112,44 | Authorized |
SDKs
curl -X POST https://api.stackin.io/api/v1/invoices \
-H "Authorization: Bearer stackin_live_••••••••••••" \
-H "Content-Type: application/json" \
-d '{
"document_type": "nfe",
"client_name": "Buyer Company Ltd",
"tax_id": "11222333000181",
"items": [{
"description": "Rosa Holambra Vermelha",
"unit_price": 112.44,
"product": { "br": { "ncm": "06031100", "cfop": "5102" } }
}]
}'{
"result": {
"access_key": "422608...50077",
"status": "authorized",
"protocol": "142260000009876",
"authorized_at": "2026-08-28T09:15:42-03:00"
}
}Real transmission to the tax authorities
Direct, secure communication with every authorizer, state or national.
Taxes and manual passthrough
Compute, break out, and pass through taxes — simple and transparent.
Official SDKs
SDKs for Python, Node.js, Go and PHP, ready to use.
Full dashboard
Track every submission, look up documents, monitor errors in real time.
Issue an invoice
by asking.
Stackin ships a ChatGPT plugin — an MCP server that exposes the API as tools. Connect the account and ask in plain language: the model confirms the data with you before anything reaches the tax authority.
Twelve operations from the conversation — issue, consult, get the PDF, cancel and more. Seven of them change a document, and every one asks first.
- Confirmation before issuingThe model reads the data back to you.
- Scoped permissions, revocableYou control what the app may do.
- Works in homologationTest at no cost before going to production.
No credit card — free homologation environment.
Issue a new invoice with the same data as the last one that succeeded
I'll prepare the NFS-e with the same data as the last invoice. Confirm the details below?
- Type
- NFS-e
- Client
- Comprador Teste Ltda
- Tax id
- 11.222.333/0001-81
- Service
- Software development SDK Node
- Amount
- R$ 5,000.00
- Environment
- Production
Yes, go ahead
The invoice was issued.
Three steps from the account to an
authorized invoice.
From signing up to issuing: a short, safe path to integrate and start sending fiscal documents with Stackin.
- 01
Configure
Register your company, address, and digital certificate.
Company dataLegal nameBuyer Company LtdaTax id11.222.333/0001-81State registration123.456.789.000EnvironmentHomologationCompany configured - 02
Integrate
Call the API with your company's key, or use a Stackin SDK.
curl -X POST https://api.stackin.io/api/v1/invoices \ -H "Authorization: Bearer stackin_live_••••••••••••" \ -H "Content-Type: application/json" \ -d '{ "document_type": "nfe", "client_name": "Buyer Company Ltd", "tax_id": "11222333000181", "items": [{ "description": "Rosa Holambra Vermelha", "unit_price": 112.44, "product": { "br": { "ncm": "06031100", "cfop": "5102" } } }] }' - 03
Ship
Issue in homologation, then production — track every submission.
Invoice issued- Number
- 000081
- Type
- NFS-e
- Client
- Buyer Company Ltda
- Amount
- R$ 5,000.00
- Protocol
- 142260000009876
- Date
- 2026-08-28 15:42
- Status
- Authorized
Start issuing fiscal documents today.
Free homologation environment — no credit card required.