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Cielo: MerchantId, MerchantKey, and the right version

In the Cielo integration, you register your store's credentials in the system — unlike Stripe and Mercado Pago, where no key ever changes hands. And the most common mistake isn't a typo: it's using the credential from one version of the Cielo platform on the other.

The two versions — and each one's credential

Webservice 1.5 (SOAP/XML)API E-commerce 3.0 (REST/JSON)
CredentialsAffiliation + Production KeyMerchantId + MerchantKey
What the 1st field isthe store's registration ID with Cieloaffiliation number
Where the credential travelsin the request bodyin the header
If missing/wrongtransaction declinedthe API blocks the transaction and returns an error
Sandboxpublic, no accreditation required
The central fact: a Webservice 1.5 credential does not work on API 3.0 — the API rejects the requests. Migrating between versions requires new credentials and a new certification process with Cielo. If your checkout stopped working after a "migration", this is the first suspect.

Which version does my virtual office use? It depends on how your project is configured in MMNWEB. When in doubt, open a support ticket before touching any credential — we'll tell you the active version and which fields to fill in.

Treat it like a username and password

Cielo itself equates MerchantId + MerchantKey to the username and password of your e-commerce. Don't share them by email, WhatsApp, screenshot, or ticket — not even with our support team (when we need to validate something, we'll point you to the secure path).

Where to get the credentials (API 3.0)

According to the official Cielo PDF (2023): log in to the Cielo website → choose the merchant account → E-commerce tab → API E-commerce CieloBraspag environment → CieloCredentialsView Merchant Key → confirmation code by email → Confirm.

Heads-up — the panel changes: more recent sources describe a different flow (API e-commerce management → API Credential), in which the MerchantKey is displayed only once at generation time and can only be obtained again through revocation (which takes ~15 min to take effect and invalidates the previous key — a real risk if the store is live; never do it as a routine step). If the screen you see differs from the PDF, check docs.cielo.com.br or Cielo support before acting.

Official endpoints and contacts

Production (API 3.0): https://api.cieloecommerce.cielo.com.br/1/sales/
Sandbox (API 3.0): https://cadastrosandbox.cieloecommerce.cielo.com.br/
E-commerce accreditation: credenciamentoecommerce@cielo.com.br · Support: cieloecommerce@cielo.com.br · 4002 9700 · 0800 570 1700

Official sources

docs.cielo.com.br (current documentation) · 1.5 vs 3.0 FAQ and migration guide (the developercielo.github.io manual has been discontinued since August 14, 2024 — cited here as legacy).

Related: Integrations overview · Stripe · Mercado Pago · Engine concepts

Checkout down or unsure about a credential?