> ## Documentation Index
> Fetch the complete documentation index at: https://repost.sh/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Python Compatibility and Security

> Supported Python runtimes, dependencies, concurrency, transport capabilities, native verification, and security posture.

| Axis                      | Supported                                                                                                                                            |
| ------------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Runtime**               | CPython 3.10 through 3.14. The native release matrix exercises the 3.10 floor and current stable 3.14.                                               |
| **Free-threaded CPython** | Not certified. Use a standard GIL build.                                                                                                             |
| **PyPy**                  | Not certified.                                                                                                                                       |
| **HTTP**                  | HTTP/2 over TLS with HTTP/1.1 fallback, or forced HTTP/1.1. Bounded connection pools are per origin.                                                 |
| **Dependencies**          | `repost-client` depends only on `h2~=4.2`. OpenTelemetry stays in the separate `repost-client-otel` distribution.                                    |
| **Concurrency**           | Synchronous, thread-safe sends. Use one worker thread per concurrent blocking send. A native asyncio API is not included in `0.4`.                   |
| **Platform**              | Trusted server-side Python only. Desktop, mobile, browser, and other untrusted clients are unsupported because the SDK carries a publish credential. |

The Python SDK is verified by native pytest tests. The suite exercises generated imports and typing, the public generated client, real runtime behavior, default HTTP/1.1 and HTTP/2 transports, proxy and TLS paths, cancellation, resource bounds, deterministic testing helpers, and response parsing. Shared JSON files provide scenario input only; Python tests select cases and make every assertion.

## Security posture

* **Transport security.** TLS verification is always enabled. The built-in transport supports custom certificate authorities, TLS 1.2 and 1.3 bounds, cipher allowlists, encrypted client keys, mutual TLS, explicit CONNECT proxies, and proxy credential providers.
* **Network policy.** Redirects are disabled. Ambient proxy environment variables are ignored; configure a proxy explicitly. Plain HTTP is limited to loopback hosts.
* **Resource limits.** Request and response bodies, response headers, decompression ratio, retained bytes, in-flight operations, connection counts, and connection lifetimes are bounded.
* **Redaction.** Configuration representations, diagnostics, observer events, telemetry, fixed error messages, and scripted request recordings contain no credentials or payload values. The SDK does not remove personal data from an event; the payload you pass is intentionally sent to Repost.
* **DNS callbacks.** Built-in socket I/O observes cancellation and deadlines. A user-supplied synchronous DNS resolver must return promptly because CPython cannot forcibly interrupt a callback that blocks forever.
* **FIPS.** This release is not FIPS-certified. It uses the Python runtime's OpenSSL and standard cryptographic facilities.

## Continue

<Columns cols={3} className="gap-y-4">
  <Card title="Configuration" icon="sliders-horizontal" href="/docs/send/python/configuration" cta="Configure" arrow="true">
    Configure deadlines, budgets, proxy, DNS, TLS, and mTLS.
  </Card>

  <Card title="SDKs" icon="package" href="/docs/send/sdks" cta="All languages" arrow="true">
    Compare the generated clients available from one schema.
  </Card>

  <Card title="Schema workflow" icon="braces" href="/docs/cli/schema" cta="Schema" arrow="true">
    Version the schema with migrations and deploy it to an environment.
  </Card>
</Columns>