Last updated September 26, 2026

StepFun in Codex — Global and China API Routes

Codex Router ships two first-party StepFun providers. The global stepfun-api route uses platform.stepfun.ai and https://api.stepfun.ai/v1; stepfun-api-cn uses platform.stepfun.com and https://api.stepfun.com/v1. Accounts, keys and billing are separate. Choose the platform that issued your key; both may be enabled together.

Models

Model	Global route	China route	Input and context
Step 5 Preview	`stepfun-api/step-5-preview`	`stepfun-api-cn/step-5-preview`	Text + image; 1M
Step 3.7 Flash	`stepfun-api/step-3.7-flash`	`stepfun-api-cn/step-3.7-flash`	Text + image; 256K
Step 3.5 Flash 2603	`stepfun-api/step-3.5-flash-2603`	`stepfun-api-cn/step-3.5-flash-2603`	Text only; 256K

These are OpenAI-compatible Chat Completions routes. The first two support low/medium/high reasoning effort; Step 3.5 Flash 2603 supports low/high. Step 5 Preview compacts at 900K.

Setup

./bin/model-router codex provider-key stepfun-api set
./bin/model-router codex providers enable stepfun-api
# For a China-platform key instead:
./bin/model-router codex provider-key stepfun-api-cn set
./bin/model-router codex providers enable stepfun-api-cn
./bin/model-router codex doctor

The key prompts hide input. On Windows, use ./codex-router.ps1 codex with the same subcommands. Fully quit and reopen Codex to refresh its model picker. The environment names are STEPFUN_API_KEY and STEPFUN_API_CN_KEY if you manage keys outside the protected local key file.