There is no separate sandbox. The same endpoints serve every key, and nothing is built until a person at Glyph releases a paid job. That makes it safe to try the full flow.

What is safe

Creating jobs. A job is an estimate until you accept it. Create as many as you need. Give test jobs a clear name such as TEST — ignore.
Attaching files. Files are private and stay with the job.
Reading. Every GET is free of side effects.

What has an effect

Accept sends a real Stripe invoice when the estimate is within your auto-quote limit. A new key has a limit of zero, so accept only records that you want a quote. Ask us to keep the limit at zero while you build, and we raise it when you are ready.
Inquiries are read by a person. Mark a test inquiry as a test in its title.

Use idempotency keys from the start

Send an Idempotency-Key on every create. Your retries then return the same record instead of a second one. See Retries and idempotency.

Check your estimate math

The estimate is deterministic: hours × the first machine's hourly rate for each operation, plus material_cost_cents, plus the setup fee, floored at the minimum charge. Read the catalog first and you can predict the total before you send the job.

Going live

Confirm your account email with us. Invoices go there.
Tell us the auto-quote limit you want.
Switch your system from test job names to real ones. Nothing else changes.