Grok 4.1 Fast
How TheRouter serves this differently from the vendor
xAI retired the upstream grok-4-1-fast-non-reasoning slug on May 15, 2026 and redirects it to grok-4.3; the vendor does not present it as a current standalone model with a separate model card.
TheRouter still exposes xai/grok-4-1-fast-non-reasoning as a listed compatibility model id with TheRouter catalog pricing, 2M context, text+image input, tools, and structured outputs. Customers should validate behavior before treating it as equivalent to the successor.
API guide
Fast chat
Use the OpenAI-compatible chat completions endpoint with the TheRouter model id. Keep this snippet for compatibility tests; prefer current xAI successors for new builds.
curl https://api.therouter.ai/v1/chat/completions \
-H "Authorization: Bearer $THEROUTER_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "xai/grok-4-1-fast-non-reasoning",
"messages": [
{"role": "system", "content": "Be concise and flag uncertainty."},
{"role": "user", "content": "Summarize the migration risks in this plan."}
]
}'Tool calls
Use narrow function schemas for fast dispatch. This non-reasoning route is a compatibility executor, so keep decision logic outside the call when correctness depends on deeper reasoning.
curl https://api.therouter.ai/v1/chat/completions \
-H "Authorization: Bearer $THEROUTER_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "xai/grok-4-1-fast-non-reasoning",
"messages": [{"role": "user", "content": "Check order ord_123 and decide whether to escalate."}],
"tools": [{"type": "function", "function": {"name": "get_order_status", "description": "Return order status by id", "parameters": {"type": "object", "properties": {"order_id": {"type": "string"}}, "required": ["order_id"]}}}],
"tool_choice": "auto"
}'Fact ledger — every claim on this page traces here
| source | URL | retrieved | |
|---|---|---|---|
| TheRouter model ID | — | — | verified |
| Upstream slug status | docs.x.ai ↗ | 2026-08-11 | verified |
| Context window | — | — | verified |
| Input modalities | — | — | verified |
| Output modalities | — | — | verified |
| Reasoning parameter | — | — | verified |
| Structured outputs | — | — | verified |
| TheRouter pricing | — | — | verified |
| Training cutoff | — | — | unknown |
| License | — | — | verified |
| Exact retired slug benchmarks | docs.x.ai ↗ | 2026-08-11 | unknown |
| Successor comparison guidance | docs.x.ai ↗ | 2026-08-11 | unknown |
| TheRouter route shape | docs.x.ai ↗ | 2026-08-11 | unknown |
| xAI retires Grok 4.1 fast slugs and redirects them to Grok 4.3 | docs.x.ai ↗ | 2026-08-11 | verified |
| Is xai/grok-4-1-fast-non-reasoning still a current xAI model? | docs.x.ai ↗ | 2026-08-11 | to verify |
| Why are there no exact benchmark scores on this page? | docs.x.ai ↗ | 2026-08-11 | to verify |