Grok 4 Fast Reasoning vs Together AI - Llama 3 8B Lite
Grok 4 Fast Reasoning (2025) and Together AI - Llama 3 8B Lite (2025) are frontier reasoning models from xAI and AI at Meta. Grok 4 Fast Reasoning ships a 2m-token context window, while Together AI - Llama 3 8B Lite ships a 8k-token context window. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Together AI - Llama 3 8B Lite is ~1150% cheaper at $0.10/1M; pay for Grok 4 Fast Reasoning only for reasoning depth.
Decision scorecard
Local evidence first| Signal | Grok 4 Fast Reasoning | Together AI - Llama 3 8B Lite |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and long-context analysis | tool-calling agents |
| Decision fit | Long context and Vision | Agents, Classification, and JSON / Tool use |
| Context window | 2m | 8k |
| Cheapest output | $2.50/1M tokens | $0.10/1M tokens |
| Provider routes | 2 tracked | 1 tracked |
| Shared benchmarks | 0 rows | 0 rows |
Decision tradeoffs
- Grok 4 Fast Reasoning has the larger context window for long prompts, retrieval packs, or transcript analysis.
- Grok 4 Fast Reasoning has broader tracked provider coverage for fallback and procurement flexibility.
- Grok 4 Fast Reasoning uniquely exposes Vision, Multimodal, and Reasoning in local model data.
- Local decision data tags Grok 4 Fast Reasoning for Long context and Vision.
- Together AI - Llama 3 8B Lite has the lower cheapest tracked output price at $0.10/1M tokens.
- Together AI - Llama 3 8B Lite uniquely exposes Function calling, Tool use, and Structured outputs in local model data.
- Local decision data tags Together AI - Llama 3 8B Lite for Agents, Classification, and JSON / Tool use.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Grok 4 Fast Reasoning
$1,625
Cheapest tracked route/tier: xAI Console
Together AI - Llama 3 8B Lite
$105
Cheapest tracked route/tier: Together AI
Estimated monthly gap: $1,520. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- No overlapping tracked provider route is sourced for Grok 4 Fast Reasoning and Together AI - Llama 3 8B Lite; plan for SDK, billing, or endpoint changes.
- Together AI - Llama 3 8B Lite is $2.40/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Vision, Multimodal, and Reasoning before moving production traffic.
- Together AI - Llama 3 8B Lite adds Function calling, Tool use, and Structured outputs in local capability data.
- No overlapping tracked provider route is sourced for Together AI - Llama 3 8B Lite and Grok 4 Fast Reasoning; plan for SDK, billing, or endpoint changes.
- Grok 4 Fast Reasoning is $2.40/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Check replacement coverage for Function calling, Tool use, and Structured outputs before moving production traffic.
- Grok 4 Fast Reasoning adds Vision, Multimodal, and Reasoning in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-09-01 | 2025-07-15 |
| Context window | 2m | 8k |
| Parameters | — | 8B |
| Architecture | decoder only | decoder only |
| License | Proprietary | Llama 3 Community |
| Openness | Proprietary | Open weights |
| Commercial use | Commercial use with conditions | Commercial use with conditions |
| Knowledge cutoff | - | 2024-03 |
Pricing and availability
| Pricing attribute | Grok 4 Fast Reasoning | Together AI - Llama 3 8B Lite |
|---|---|---|
| Input price | $1.25/1M tokens | $0.10/1M tokens |
| Output price | $2.50/1M tokens | $0.10/1M tokens |
| Providers |
Capabilities
| Capability | Grok 4 Fast Reasoning | Together AI - Llama 3 8B Lite |
|---|---|---|
| Vision | Yes | No |
| Multimodal | Yes | No |
| Reasoning | Yes | No |
| Function calling | No | Yes |
| Tool use | No | Yes |
| Structured outputs | No | Yes |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: Grok 4 Fast Reasoning, multimodal input: Grok 4 Fast Reasoning, reasoning mode: Grok 4 Fast Reasoning, function calling: Together AI - Llama 3 8B Lite, tool use: Together AI - Llama 3 8B Lite, and structured outputs: Together AI - Llama 3 8B Lite. Both models share the core language-model surface, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Grok 4 Fast Reasoning lists $1.25/1M input and $2.50/1M output tokens on the cheapest tracked provider, while Together AI - Llama 3 8B Lite lists $0.10/1M input and $0.10/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Together AI - Llama 3 8B Lite lower by about $1.52 per million blended tokens. Availability is 2 providers versus 1, so concentration risk also matters.
Choose Grok 4 Fast Reasoning when reasoning depth, larger context windows, and broader provider choice are central to the workload. Choose Together AI - Llama 3 8B Lite when provider fit and lower input-token cost are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Grok 4 Fast Reasoning or Together AI - Llama 3 8B Lite?
Grok 4 Fast Reasoning supports 2m tokens, while Together AI - Llama 3 8B Lite supports 8k tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Grok 4 Fast Reasoning or Together AI - Llama 3 8B Lite?
Together AI - Llama 3 8B Lite is cheaper on tracked token pricing. Grok 4 Fast Reasoning costs $1.25/1M input and $2.50/1M output tokens. Together AI - Llama 3 8B Lite costs $0.10/1M input and $0.10/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Grok 4 Fast Reasoning or Together AI - Llama 3 8B Lite open source?
Grok 4 Fast Reasoning is listed under Proprietary. Together AI - Llama 3 8B Lite is listed under Llama 3 Community. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Grok 4 Fast Reasoning or Together AI - Llama 3 8B Lite?
Grok 4 Fast Reasoning has the clearer documented vision signal in this comparison. If vision is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Which is better for multimodal input, Grok 4 Fast Reasoning or Together AI - Llama 3 8B Lite?
Grok 4 Fast Reasoning has the clearer documented multimodal input signal in this comparison. If multimodal input is mission-critical, validate it against the provider endpoint because model-level support and API-level exposure can differ.
Where can I run Grok 4 Fast Reasoning and Together AI - Llama 3 8B Lite?
Grok 4 Fast Reasoning is available on Microsoft Foundry and xAI Console. Together AI - Llama 3 8B Lite is available on Together AI. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
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Last reviewed: 2026-05-20. Data sourced from public model cards and provider documentation.