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Sandbox & test keys

Fabric’s sandbox is a full, working environment reachable with an sk_test_ key. You can send SMS and email, preview definitions, receive webhooks, and read the wallet before you fund an account, register a sender ID, or verify a domain. Nothing you do in sandbox touches a real recipient or spends real money.

What the sandbox does

Section titled “What the sandbox does”
  • Sends resolve on a virtual path. SMS goes to a virtual number; email goes to a fake provider. No carrier, no inbox, no cost against real funds.
  • Everything else is real. Rendering, variable validation, encoding and segment counting, size tiers, cost calculation, idempotency, delivery states, and webhook signing all behave exactly as they do live.
  • Delivery is deterministic. Virtual sends resolve immediately, so you can build and test your webhook consumer without waiting on a network.
  • Inbound replies can be simulated. The dashboard’s virtual phone can reply to a sandbox message, including the STOP / START / HELP keywords, which exercise consent handling.

What the sandbox does not do

Section titled “What the sandbox does not do”
  • It never contacts a real handset or inbox.
  • It does not require a funded wallet or an approved sender ID.
  • It is not a load or latency test of the live carrier route.

Test keys are still secrets

Section titled “Test keys are still secrets”

An sk_test_ key cannot spend real money, but it can read and mutate everything in your sandbox. Keep it server-side, out of client bundles and public repositories, exactly like a live key. Environments are isolated: a sandbox key sees only sandbox definitions, activity, and webhook endpoints.