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iFirma API and MCP server

iFirma's API has no calls for downloading purchase invoices from KSeF or sending payment reminders. Sign in to iFirma once in your own Cloud Browser, and your AI agent does the work there for you. The same tools work over MCP for agents and as a REST API for scripts.

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Not affiliated with iFirma.

iFirma has no API for this. So we run one for you.

iFirma's own API, a GitHub MCP server and Cotlet compared
What you need iFirma's APIGitHub MCP serverCotlet
KSeF purchase invoices, payment reminders No Partly Yes, 14 tools
Acts as you, signed in 24/7 No No Yes, Cloud Browser
Fixed for you when iFirma changes N/A No Yes, tested every 6h
Runs with your laptop off N/A No Yes, hosted

Checked Oct 14, 2026. Sources: iFirma API: general information and limits · iFirma API: activation · iFirma API: authorization header · iFirma API: sending an invoice to KSeF

Your own Cloud Browser, on 24/7. Sign in once. We keep it connected.

  1. 01Sign in to iFirma in your own Cloud Browser

  2. 02Connect it for your agents

  3. 03Cotlet keeps it signed in and working

How do I connect iFirma to Claude, ChatGPT or my code?

AI agents connect over MCP, scripts call the REST API. Both reach the same 14 tools with one API key.

For AI agents: MCP

Add Cotlet to your agent once. iFirma and every other app you connect show up as its tools.

  • Claude
  • ChatGPT
  • OpenClaw
  • Hermes
  • GrokBot
  • Cursor
  • n8n
  • Any MCP client
  1. 1

    Add Cotlet to your agent

    Claude Code
    claude mcp add --transport http cotlet \
  https://cotlet.dev/mcp/v1 \
  --header "Authorization: Bearer $COTLET_API_KEY"
    Cursor
    {
  "mcpServers": {
    "cotlet": {
      "url": "https://cotlet.dev/mcp/v1",
      "headers": {
        "Authorization": "Bearer ${COTLET_API_KEY}"
      }
    }
  }
}
    Codex
    # ~/.codex/config.toml
[mcp_servers.cotlet]
url = "https://cotlet.dev/mcp/v1"
bearer_token_env_var = "COTLET_API_KEY"

    Paste the snippet for your client. The same server and key serve every app you connect, so you do this once.

For scripts: REST API

Every tool is an endpoint under /api/v1/ifirma with its own method and path, such as POST /api/v1/ifirma/contractors/{contractor_id}/invoices, with the same API key. Our open-source repo has ready scripts to start from.

REST API docs

What can the iFirma API and MCP server do?

14 tools on your own iFirma account. Agents call them as operations of the MCP tools ifirma_read and ifirma_write; scripts call each one at its own REST endpoint, with the same inputs and answers.

API reference
iFirma tools in Cotlet's MCP server and REST API
Tool What it does Access
list_invoices Sales invoices for a date range, with totals, payment and KSeF status. read
get_invoice One invoice with its lines, buyer, payments and KSeF status. read
get_invoice_pdf The invoice as a PDF file, base64 encoded. read
list_contractors Contractors from your list, searchable by name or tax number. read
list_ksef_purchase_invoices Invoices that suppliers sent to you in KSeF and you have not booked yet. read
create_contractor Add a contractor to your iFirma list. write
save_invoice_draft Save an invoice as a draft without a number, to review and issue in the app. write
issue_invoice Issue a domestic invoice for a contractor with one or more lines. writeasks first
send_invoice_to_ksef Send one issued invoice to the Polish KSeF e-invoicing system. writeasks first
send_invoice_email Email an issued invoice to the buyer, with the invoice attached. writeasks first
record_payment Record a payment received on an invoice. writeasks first
book_ksef_purchase_invoice Book a purchase invoice from KSeF as a cost. writeasks first
add_expense Add a cost document by hand: goods purchase, business cost or phone and internet bill. writeasks first
send_payment_reminder Email a Ponaglenie, Monit or Wezwanie do zapłaty for an unpaid invoice. writeasks first

Scroll the table for all 14 tools.

Ask in plain words. Your agent does the rest.

All iFirma use cases

Is it safe to connect iFirma?

You sign in yourself in your own Cloud Browser, we never save your password, and anything that reaches your readers waits for your OK. The browser profile is encrypted in the EU. Independent scanners grade cotlet.dev A+.

Security overview

How much do the iFirma API and MCP server cost?

One price for both: a tool call costs the same over MCP or REST. Free 7-day trial with 2,000 credits, no card needed. Then one-time credit packs, no subscription, valid 12 months. Most calls use 25 credits, and your Cloud Browser uses 50 credits a day while iFirma is enabled for agents, so 20 calls a day come to 550 credits.

See full pricing
Cotlet credit packs: price, credits and calls at 25 credits each
Credits Price, one time Calls at 25 credits Per 1,000 credits
5,000 $29 200 $5.80
15,000 $79 600 $5.27
32,000 $149 1,280 $4.66
60,000 $249 2,400 $4.15

Only successful calls use credits; failed calls and timeouts cost nothing. At a balance of 0 calls pause, never a surprise charge. Authenticate with the Authorization: Bearer header.

Questions

Does iFirma have an API?

Yes. iFirma has a documented JSON API that issues invoices, lists them, records payments, sends them by email and to KSeF, and adds cost documents (checked 14 Oct 2026). It has no official MCP server in its documentation. Every request is signed with one of four keys (subscriber, invoice, receipt, expense), you activate API access in your account first, and 100 requests per minute and 15,000 per day apply.

How do I get access?

Sign up free, open iFirma under Integrations in the console and press Request access. Your free trial starts with your account, no card needed.

Is the MCP server different from the API?

No, only the way in. Cotlet builds each integration as a REST API and puts an MCP server on top, so both have the same 14 tools, the same inputs and answers, one API key and one price. AI agents such as Claude, ChatGPT or Cursor use MCP; scripts, cron jobs and HTTP steps in n8n, Make or Zapier use the REST API.

What is the Cloud Browser?

Your own Chrome that Cotlet runs for you in the EU, around the clock. You open it from the console, sign in to iFirma yourself and press Enable for agents. Your agent's calls go through it, from its IP with its cookies, so iFirma sees the browser you signed in with. Password saving is off and the profile is stored encrypted with AES-256-GCM.

Can my agent act without asking me?

Not on anything that reaches other people: issue_invoice, send_invoice_to_ksef, send_invoice_email, record_payment, book_ksef_purchase_invoice, add_expense, send_payment_reminder wait for your OK by default. You can switch that off per tool for scheduled runs.

Which iFirma packages does KSeF purchase invoice download work on?

iFirma lists downloading from KSeF for Księgowość internetowa and for the faktura plus and darmowa faktura packages. Booking the invoices is done under Wydatki.

Should I use a iFirma MCP server from GitHub instead?

Pick one if you want the code on your own computer and do not mind the upkeep: you install it, sign it in and fix it when iFirma changes. Pick Cotlet if you want it hosted and kept working for you.

Can I use it in n8n, Make or Zapier?

Yes. Add https://cotlet.dev/mcp/v1 in n8n's MCP Client node, or call the REST endpoints from an HTTP step in Make or Zapier.

Who runs Cotlet?

Cotlet is run by Take Group, a Polish software company working since 2019. Take Group runs about 3,200 websites on its own systems and has its own DevOps team for infrastructure security. We built and used integrations like this inside the company for years before opening them as Cotlet.

Is Cotlet affiliated with iFirma?

No. Cotlet is independent and not affiliated with iFirma.

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