How to Connect Tezga eKasa to ChatGPT via MCP

💡 No install? Use cloud.anythingmcp.com directly. Sign in, click Connectors → Tezga eKasa, paste your credentials, mint an MCP API key and you're done. No Docker, no git clone, no local server.

Tezga eKasa + ChatGPT

Tezga eKasa, the online fiscal cash register for Serbian companies: fiscal setup and tax labels, status and fiscal data of issued receipts, and bank transactions. Issuing, cancelling or refunding receipts and writing customers and items are included, installed switched off.

Prerequisites

See the full setup instructions baked into the connector (visible in the in-app store when you select the connector). The required environment variables for this connector are:

TEZGA_API_KEY

Step 1 — Get credentials

Setting up takes about 3 minutes. You need a Tezga account on a plan with API access and an API key.

1. API access is part of the Posao and Biznis plans (or the Enterprise level). On other plans every call answers 402.
2. In Tezga open Podešavanja > Integracije > API ključevi, name a key (e.g. AnythingMCP) and create it. It is shown only once: copy it into TEZGA_API_KEY. Keys start with tzg_ followed by 48 hex characters. Use a separate key for this connector so you can pause or delete it on its own; you can also bind it to the IP addresses of your AnythingMCP server there.
3. Install the connector and run tezga_get_account_setup to check the key and see the environment.

The key travels in the X-Tezga-Api-Key header. Keys rotate every 90 days: Tezga e-mails a reminder on day 76, and you paste the new key into the connector before the old one is switched off. A read-only key is enough for the read tools; writes with it answer 403.

Environment first: test and production keys look the same, because the environment belongs to the account. tezga_get_account_setup returns okruzenje: produkcija (real receipts reported to the Tax Administration), sandbox (the official test environment), simulacija (demo, PFR numbers start with MOCK) or nepovezano (no security element, fiscalisation refused). The AI tells you which one it is before any write.

What it reads: the account's fiscal setup (the environment, whether the company is in the VAT system and subject to fiscalisation, and the tax labels); a document (receipt, proforma, refund) by its Tezga id, or the document issued for one of your order numbers (externalId), with its number, type, status (nacrt draft, izdat issued, storniran cancelled), total with VAT, payment method, fiscal data (PFR number and time, receipt counter, verification URL; null when not fiscalised) and the public PDF link javniPdfUrl, which opens without login; and the company's bank transactions imported from statements, newest first (smer uplata for incoming, isplata for outgoing, since for a start time), for matching payments to invoices.

Switched off at install: tezga_issue_receipt (a fiscal receipt or a proforma, or with tok sef an e-invoice to SEF; idempotent per externalId, so the same order number never creates a second receipt), tezga_refund_document (storno or refund, issued as a new document referring to the original), tezga_upsert_customers and tezga_upsert_products (matched by PIB, e-mail or name, or by item code; nothing is deleted). A fiscal receipt cannot be undone, only refunded, so an administrator turns these on deliberately. Even then the AI shows you the lines, amounts and environment and waits for your yes.

Amounts and tax: prices are RSD including VAT (cenaSaPdv). Tax rates are 20, 10, 0 or oslobodjeno (exempt). A company outside the VAT system has every line recorded as exempt, whatever rate is sent.

Limits: 240 reads and 120 writes per minute per company by default; responses carry X-RateLimit-Limit, X-RateLimit-Remaining and X-RateLimit-Reset, and 429 comes with Retry-After. At most 500 lines per receipt and 500 customers or items per call; request bodies up to 512 KB.

Common errors: 401 means a missing or wrong key. 402 means a plan without API access or an inactive subscription (error says which). 403 means a read-only key used for a write, a till-terminal key, or a request from an IP that is not on the key's list. 404 means the document does not exist in your company. 409 means the action is not allowed (not issued, already partly refunded) or the same externalId is being processed. 422 lists field or rule errors in fields. 202 on a write means the document exists but the Tax Administration has not accepted it yet; Tezga retries by itself, so the AI does not send it again.

Step 2 — Install the adapter

curl -fsSL https://raw.githubusercontent.com/HelpCode-ai/anythingmcp/main/docker-compose.quickstart.yml -o docker-compose.yml
printf 'JWT_SECRET=%s\nENCRYPTION_KEY=%s\n' "$(openssl rand -hex 32)" "$(openssl rand -hex 32)" > .env
docker compose up -d

Step 3 — Add the connector in ChatGPT

Your server URL: in AnythingMCP, open MCP Servers → the server this connector is on, and copy its URL (https://cloud.anythingmcp.com/mcp/…). Use it wherever this guide shows YOUR_SERVER_ID.

ChatGPT adds MCP servers as plugins on its Plugins page, on the web and on paid plans. Developer mode is no longer needed. In a Business workspace only admins and owners can add one; in Enterprise and Edu an admin can grant the Create plugins with MCPs permission.

1. Go to chatgpt.com/plugins, click Add, then Add custom MCP server.
2. Enter a name, e.g. Name: Tezga eKasa.
3. Under Connection, enter the Server URL https://cloud.anythingmcp.com/mcp/YOUR_SERVER_ID and keep Authentication on OAuth.
4. Select I understand and want to continue, then Create as a plugin. When ChatGPT asks, sign in to AnythingMCP and allow access.
5. Install the new plugin from your personal plugins, then type @ in a chat and pick it.

Available tools

Example prompts

• "Which environment is our Tezga account in, and is the company in the VAT system?"
• "Does order 10452 already have a fiscal receipt? Give me the PFR number and the public PDF link."
• "List the incoming bank payments since Monday so I can match them to our invoices."
• "Is the receipt for order 10398 issued or cancelled, and what was its total?"
• "Which tax labels does our account use, and which rate does each one stand for?"

FAQ

Does the free ChatGPT plan work with custom MCP servers? OpenAI documents custom MCP servers for paid plans only; the Free plan is not on its list.

Next steps

• Connector landing page
• Connect to Claude
• Connect to Cursor
• Connect to Gemini
• Connect to Meta Muse
• Connect to Microsoft Copilot