Grok 4.3 Beta vs Step 3.5 Flash
Grok 4.3 Beta (2026) and Step 3.5 Flash (2026) are frontier-tier reasoning models from xAI and StepFun. Grok 4.3 Beta ships a 2M-token context window, while Step 3.5 Flash ships a 256K-token context window. This comparison covers specs, pricing, capabilities, benchmarks, provider availability, and production fit. It focuses on practical selection signals rather than broad model-family marketing. The goal is to make the tradeoff clear before deeper testing.
Grok 4.3 Beta fits 8x more tokens; pick it for long-context work and Step 3.5 Flash for tighter calls.
Specs
| Released | 2026-04-17 | 2026-01-29 |
| Context window | 2M | 256K |
| Parameters | ~0.5T | 196B (11B active) |
| Architecture | - | mixture of experts |
| License | Proprietary | Open Source |
| Knowledge cutoff | - | - |
Pricing and availability
| Grok 4.3 Beta | Step 3.5 Flash | |
|---|---|---|
| Input price | - | $0.1/1M tokens |
| Output price | - | $0.3/1M tokens |
| Providers | - |
Capabilities
| Grok 4.3 Beta | Step 3.5 Flash | |
|---|---|---|
| Vision | ||
| Multimodal | ||
| Reasoning | ||
| Function calling | ||
| Tool use | ||
| Structured outputs | ||
| Code execution |
Benchmarks
No shared benchmark rows are currently sourced for this pair.
Deep dive
The capability footprint differs most on vision: Grok 4.3 Beta, multimodal input: Grok 4.3 Beta, function calling: Grok 4.3 Beta, tool use: Grok 4.3 Beta, and structured outputs: Grok 4.3 Beta. Both models share reasoning mode, 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.
Pricing coverage is uneven: Grok 4.3 Beta has no token price sourced yet and Step 3.5 Flash has $0.1/1M input tokens. Provider availability is 0 tracked routes versus 1. Treat unknown pricing as an integration gap, then verify the route you will actually call before estimating production spend.
Choose Grok 4.3 Beta when long-context analysis and larger context windows are central to the workload. Choose Step 3.5 Flash when provider fit and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship. This keeps the decision grounded in measurable tradeoffs instead of brand-level assumptions. It also helps separate model capability from provider packaging, which can change cost and latency.
FAQ
Which has a larger context window, Grok 4.3 Beta or Step 3.5 Flash?
Grok 4.3 Beta supports 2M tokens, while Step 3.5 Flash supports 256K tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Is Grok 4.3 Beta or Step 3.5 Flash open source?
Grok 4.3 Beta is listed under Proprietary. Step 3.5 Flash is listed under Open Source. 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 4.3 Beta or Step 3.5 Flash?
Grok 4.3 Beta 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 4.3 Beta or Step 3.5 Flash?
Grok 4.3 Beta 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.
Which is better for reasoning mode, Grok 4.3 Beta or Step 3.5 Flash?
Both Grok 4.3 Beta and Step 3.5 Flash expose reasoning mode. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Grok 4.3 Beta and Step 3.5 Flash?
Grok 4.3 Beta is available on the tracked providers still being sourced. Step 3.5 Flash is available on OpenRouter. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-04-25. Data sourced from public model cards and provider documentation.