Environments

Sandbox and live environments for development and production

mintfax has two environment types: sandbox and live. When you create an account, one of each is set up automatically. You can create additional environments of either type to manage activity separately - for example, separate live environments for staging and production, or per-client sandbox environments for integration testing.

Each environment has its own fax records, webhook endpoints, and settings. Operational data never crosses between environments.

Sandbox and live

Sandbox and live are peers on the mintfax API. The same routes, request and response shapes, error codes, events, webhook delivery and signing, idempotency behavior, credit hold and capture lifecycle, and dashboard surfaces apply in both. Exactly three things differ:

Aspect	Sandbox	Live
Charges	Simulated top-ups, card never touched	Real Stripe charges, card on file debited
Delivery	Deterministic simulator; faxes never reach PSTN	Real carrier; faxes delivered to real fax machines
Activation	Always active	Requires first successful live credit purchase

Everything outside this table is identical between the two.

How routing works

The API key prefix determines which environment handles the request. There is no separate base URL or environment toggle.

Prefix	Environment	Effect
mfx_test_	Sandbox	Routed to sandbox. No real faxes sent.
mfx_live_	Live	Routed to production. Real faxes delivered.

See Authentication for key management and rotation.

What’s isolated

Each environment has its own:

• Fax records - sandbox faxes never appear in live queries, and vice versa
• Webhook endpoints - delivery notifications are scoped per environment
• Fax settings - cover page defaults, retry policy, and other configuration

Credits and API keys live at the account, not the environment. Each account has one virtual sandbox credit pool and one live credit pool, both shared across every environment of that type under the account. API keys are issued by the account and scoped to a specific environment via their prefix. See Credits and Authentication.

No migration path

Environments are deliberately isolated. There is no automatic migration of fax records, settings, or webhook configuration from sandbox to live. This keeps test data from contaminating production.

Configure your live environment’s webhook endpoints, fax settings, and API keys independently. Credits, payment method, and members live at the account, so those are already in place.

Created on registration

When you register, both environments are created automatically. Two API keys are returned: an mfx_test_ key scoped to the sandbox environment for sending test faxes, and an mfx_acct_ key scoped to the account for managing billing, keys, and members. The sandbox starts with a seeded simulated balance, so you can send sandbox faxes immediately.

Your live environment is ready but inactive until the first successful live credit purchase. See Account activation for the gate and the flow.

Next

Sandbox

Sandbox numbers, simulated outcomes, and balance testing

Live

Real fax delivery and production behavior