Developer documentationSDKs

Once Email SDKs

Open-source SDK candidates for the Once Email receive-only API, with tested downloads for seven ecosystems.

View sourceSHA256SUMSRead the API contractRead the SDK testing guide

7 Once Email SDKs

Use one reviewed OpenAPI contract from TypeScript, Python, Java, Go, .NET, PHP, or Ruby. Source, reference documentation, versions, and local-download archives are public.

Linux · macOS · Windows

Native CI has passed on Linux, macOS, and Windows. TypeScript and Python include automated tests; Java, Go, .NET, PHP, and Ruby pass their available native build or syntax gates.

Release status

These are public prerelease candidates, not npm, PyPI, Maven Central, NuGet, Packagist, or RubyGems releases. Pin the archive version and verify SHA256SUMS before use.

Every archive includes code and documentation. The release also provides MANIFEST.txt and SHA256SUMS.
Choose an SDK

Use the language already owned by your test service. Do not add a second runtime only for mailbox polling; the seven clients share the same receive-only contract.

Verify before installing

Download one immutable archive, compare its SHA-256 value with SHA256SUMS, read its bundled README and pin the version in your project.

Keep the workflow bounded

Create one inbox per authorized test, poll within one deadline, treat 429/503 separately, avoid logging messages or codes, and always delete the inbox in finally.

SDK Demo

Download code, docs, and demo together

Versioned archives include source, documentation, safety boundaries, and checksums.

Local downloadBrowse demos

Complete usage guide

Choose your SDK

Use only an application you own or are explicitly authorized to test. Once Email receives mail only; it does not send mail or automate third-party registrations.

Documentation and source are public. API calls remain controlled. SDKs and the Skill are versioned prerelease downloads, not language-registry releases. Public documentation and prerelease downloads do not grant API access. API key creation and live calls are not publicly open.

Open SHA256SUMS before extracting the file.

Choose your SDKSHA256SUMS

Exact local starting point

Use the exact local build/install command in its README; registry installation is not available.

From download to a clean first run

  1. Choose the language already used by the authorized test service.
  2. Download that language archive and verify its SHA-256 before extracting it.
  3. Confirm SDK 0.1.0-private.2, API contract 0.5.0-private-beta, runtime, license, and prerelease status.
  4. Use the exact local build/install command in its README; registry installation is not available.
  5. Proceed only with explicitly authorized API access and already issued, valid credentials with the minimum necessary permissions. Store them in a process secret facility; without this access, stop at reviewing the documentation and downloads. Inject the API key through a process secret facility; create, list, read, and handle errors within one deadline.
  6. Delete in finally on success or failure and never print addresses, messages, codes, links, or keys.

Failure and recovery

Keep 400, 401, 403, 404, 413, 429, and 503 distinct. Timeout, ambiguity, extraction, assertion, and cleanup are also different failures. Retry only within one deadline and never turn a dependency failure into an empty inbox.

Browse public sourceRead the practical guide