Grok Code Fast 1 vs Mistral Medium 3.5

xAI · US  |  Mistral AI · France · Updated June 2026

Quick verdict

Pick Grok Code Fast 1 for fast, cheap agentic coding at $0.20/$1.50 or low-latency code generation and terminal tasks. Pick Mistral Medium 3.5 for strong intelligence-for-size — artificial analysis intelligence index 30, near the top of its price tier or 128b dense open-weight model — self-hostable. Choose Mistral Medium 3.5 if you need self-hosting or data privacy; Grok Code Fast 1 if you want a managed API.

Grok Code Fast 1 (xAI, US) and Mistral Medium 3.5 (Mistral AI, France) line up two different AI ecosystems against each other — a comparison that is as much about cost philosophy and openness as raw capability. Grok Code Fast 1 is xAI's speed-tier coding model at $0.20/$1.50 with a 256K window — cheap, fast agentic code over frontier quality. Mistral Medium 3.5 is mistral's efficient 128B open-weight model — a single dense model unifying reasoning and coding that punches above its size on independent tests (AA Index 30). They diverge most on price and open vs. closed weights — each quantified below from the models' real specs.

Key differences at a glance

Side-by-side specs

SpecGrok Code Fast 1Mistral Medium 3.5
ProviderxAI (US) Mistral AI (France)
ReleasedAugust 28, 2025 April 29, 2026
Context window256K (~384 pages) 256K (~384 pages)
Price (in/out)$0.2/$1.5 per 1M tokens $1.5/$7.5 per 1M tokens
Open weight?No — API only Yes — self-hostable
Modalitiestext, code text, image, code
SWE-Bench VerifiedNot published Not published
MRCR v2 @ 1MNot published Not published

Who wins what

Fast, cheap agentic coding at $0.20/$1.50

Grok Code Fast 1

At $0.2/$1.5 per 1M tokens it undercuts Mistral Medium 3.5 ($1.5/$7.5 per 1M tokens), and that gap compounds at volume.

Low-latency code generation and terminal tasks

Grok Code Fast 1

XAI's speed-tier coding model at $0.20/$1.50 with a 256K window — cheap, fast agentic code over frontier quality — and it runs cheaper at $0.2/$1.5 per 1M tokens.

High-volume coding pipelines where speed beats peak quality

Grok Code Fast 1

Grok Code Fast 1 lists high-volume coding pipelines where speed beats peak quality among its strengths; Mistral Medium 3.5 does not.

Strong intelligence-for-size — Artificial Analysis Intelligence Index 30, near the top of its price tier

Mistral Medium 3.5

Mistral's efficient 128B open-weight model — a single dense model unifying reasoning and coding that punches above its size on independent tests (AA Index 30) — and its weights are open while Grok Code Fast 1 is API-only.

128B dense open-weight model — self-hostable

Mistral Medium 3.5

Open weights make this possible at all — Grok Code Fast 1 is API-only, so it cannot leave the vendor's servers.

Unifies reasoning and coding into one model with an adjustable reasoning effort

Mistral Medium 3.5

Grok Code Fast 1 is comparatively weak here — a speed-tier coding model, not a frontier reasoner

Lowest cost at scale

Grok Code Fast 1

At $0.2/$1.5 per 1M tokens, it is the cheaper of the two — the gap dominates the bill on high-volume workloads.

Which should you pick?

A cost-sensitive startup shipping high volume

Grok Code Fast 1

At $0.2/$1.5 per 1M tokens it undercuts Mistral Medium 3.5, and on millions of tokens that margin decides the monthly bill.

A team with data-privacy or self-hosting needs

Mistral Medium 3.5

Open weights let you run it on your own hardware; Grok Code Fast 1 is API-only.

Anyone whose priority is fast, cheap agentic coding at $0.20/$1.50

Grok Code Fast 1

It is specifically built for that.

Anyone whose priority is strong intelligence-for-size — artificial analysis intelligence index 30, near the top of its price tier

Mistral Medium 3.5

That is its strongest area.

An enterprise with regional data-residency rules

Grok Code Fast 1 or Mistral Medium 3.5

Origin (US vs France) affects where data is processed and which compliance regime applies — check the provider's terms for your region.

Grok Code Fast 1: where it fits

XAI's speed-tier coding model at $0.20/$1.50 with a 256K window — cheap, fast agentic code over frontier quality. Released August 28, 2025 by xAI, it is built for fast, cheap agentic coding at $0.20/$1.50, low-latency code generation and terminal tasks, high-volume coding pipelines where speed beats peak quality, and a 256K window sized for real codebases.

Its trade-offs are real: text and code only — no image, audio or video input, xAI did not publish a SWE-Bench Verified score, a speed-tier coding model, not a frontier reasoner, and narrow focus — built for code, not general knowledge work. At $0.2 in / $1.5 out per million tokens, it sits in the budget price band.

Mistral Medium 3.5: where it fits

Mistral's efficient 128B open-weight model — a single dense model unifying reasoning and coding that punches above its size on independent tests (AA Index 30). Released April 29, 2026 by Mistral AI, it is built for strong intelligence-for-size — Artificial Analysis Intelligence Index 30, near the top of its price tier, 128B dense open-weight model — self-hostable, unifies reasoning and coding into one model with an adjustable reasoning effort, and 256K context with text and image input.

Its trade-offs: below the absolute frontier — a value/efficiency pick, not a flagship-beater, output pricing ($7.50/M) is higher than the cheapest Chinese rivals, license framing ('open' vs enterprise) varies across sources — confirm terms for commercial use, and no native video or audio. At $1.5 in / $7.5 out per million tokens, it sits in the mid price band.

The bottom line for this matchup

The defining split here is open vs. closed. Mistral Medium 3.5 gives you weights you control — self-host it, fine-tune it, keep data in-house, pay only for hardware. Grok Code Fast 1 gives you a managed, always-updated API with no infrastructure to run. Teams with GPUs, privacy requirements, or huge volume often favour the open model; teams that want zero ops and the latest capabilities favour the closed one. Capability is close enough that this operational question, not the benchmark, usually decides it.

Want both Grok Code Fast 1 and Mistral Medium 3.5 without two subscriptions? LumiChats gives you these plus 40+ models under one ₹69/day pass (about $1/day) — draft with one, cross-check with the other.

See pricing

Frequently asked questions

Is Grok Code Fast 1 or Mistral Medium 3.5 better for coding?

Public SWE-Bench figures are not available for either model, so the honest test is your own repository — run an identical real bug through both. By design, Grok Code Fast 1 leans toward fast, cheap agentic coding at $0.20/$1.50 while Mistral Medium 3.5 leans toward strong intelligence-for-size — artificial analysis intelligence index 30, near the top of its price tier, and that positioning usually predicts which feels better on your codebase.

Which is cheaper, Grok Code Fast 1 or Mistral Medium 3.5?

Mistral Medium 3.5 is open-weight, so self-hosting means no per-token fee (you pay for hardware instead), while Grok Code Fast 1 is API-metered at $0.2/$1.5 per 1M tokens. For most teams without GPUs, the API model is cheaper to start; at very high volume, self-hosting can win.

Which has the bigger context window?

Both advertise 256K (~384 pages). Remember advertised ≠ usable: recall typically degrades before the ceiling.

Can I use both Grok Code Fast 1 and Mistral Medium 3.5 together?

Yes — a multi-model platform like LumiChats gives you Grok Code Fast 1, Mistral Medium 3.5 and 40+ others under one ₹69/day pass (about $1/day), so you can draft with one and cross-check with the other instead of buying two subscriptions.

Which is newer, Grok Code Fast 1 or Mistral Medium 3.5?

Mistral Medium 3.5 — released April 29, 2026, about 8 months after Grok Code Fast 1.

Related comparisons

Specifications and benchmarks reflect publicly reported figures as of June 2026 and may change as providers release updates. Always verify on your own workload.