Grok Build 0.1

What is disclosed

Grok Build 0.1 entered early access on 19 May 2026.¹¹1xAI, API release notes, entries of 14 May and 19 May 2026. https://docs.x.ai/developers/release-notes The xAI company timeline marks it on the API ten days later, on 29 May.²²2xAI, company timeline, entries "Grok Build 0.1 on API" of 29 May 2026 and "Grok Build is Now Open Source" of 15 July 2026, read in the Internet Archive copy of 21 September 2026. https://x.ai/company and https://web.archive.org/web/20260921183023/https://x.ai/company. Arithmetic: 19 May + 10 days = 29 May. The release note calls it "SpaceXAI's coding model, trained specifically for agentic coding workflows".¹¹ xAI has published nothing on how it is built or how large it is.

The window is 256,000 tokens, and xAI gives no output limit.³³3xAI, Grok Build 0.1 model page, docs.x.ai, read 29 September 2026. https://docs.x.ai/developers/models/grok-build-0.1 The model takes text and images, and it can reason before it answers in text.³³ Images follow the general limit of 20 MiB each, in JPEG or PNG.⁴⁴4xAI, Models overview, docs.x.ai, last updated 21 September 2026. https://docs.x.ai/developers/models

Grok Build is also the name of xAI's coding agent for the terminal, in beta since 14 May 2026.¹¹ The agent runs interactively or headless in scripts, and it speaks the Agent Client Protocol.¹¹ It has been open source since 15 July 2026, though the model has no open weights.²² The agent's default model is now Grok 4.7, and Grok 4.7 Fast, the same model on faster infrastructure, runs inside it too.⁵⁵5xAI, Grok 4.7 overview, docs.x.ai, last updated 28 September 2026. https://docs.x.ai/developers/grok-4-7

What is new

Grok Build 0.1 took over from grok-code-fast-1, one of the models xAI retired on 15 May 2026.⁶⁶6xAI, Grok model retirement on 15 May 2026, migration guide, last updated 2 September 2026. https://docs.x.ai/developers/migration/may-15-retirement Requests to that slug are now served by Grok Build 0.1.⁶⁶ xAI says the newer model brings "significantly improved agentic coding and web dev capabilities".⁶⁶

The old name survives as an alias. The model page lists three aliases in all, each a form of grok-code-fast.³³

xAI's own model guide now points to Grok 4.7 for code as well as for chat.⁴⁴

Using it

Its API name is grok-build-0.1.³³ It costs $1.00 per million input tokens and $2.00 per million output tokens, with cached input at $0.20.⁷⁷7xAI, API pricing, docs.x.ai, read 29 September 2026: grok-build-0.1 at $1.00 input, $0.20 cached and $2.00 output; from 200K prompt tokens, $2.00, $0.40 and $4.00. https://docs.x.ai/developers/pricing. Arithmetic: 2.00 / 1.00 = 0.40 / 0.20 = 4.00 / 2.00 = 2. At 200K prompt tokens or more, every token in the request costs twice as much.⁷⁷

Batch requests are not accepted.³³ It is served from us-east-1 and us-west-2. By default the limits are 37 requests per second and 10,000,000 tokens per minute.³³ Function calling and structured outputs are supported.³³

Grok 4.7 costs twice as much per input token and three times as much per output token. Its context window is about twice as large.⁸⁸8xAI, Grok 4.7 model page, docs.x.ai, read 29 September 2026: $2 input and $6 output, 500,000 tokens of context. https://docs.x.ai/developers/models/grok-4.7. Arithmetic: 2 / 1 = 2; 6 / 2 = 3; 500,000 / 256,000 = 1.95.