| Signal | Grok 4 Fast | Delta | Step 3.5 Flash (free) |
|---|---|---|---|
Capabilities | 100 | +50 | |
Benchmarks | 70 | +70 | |
Pricing | 1 | -29 | |
Context window size | 100 | +14 | |
Recency | 99 | -1 | |
Output Capacity | 75 | -15 | |
| Overall Result | 3 wins | of 6 | 3 wins |
27
days ranked higher
2
days
1
days ranked higher
xAI
StepFun
Step 3.5 Flash (free) saves you $45.00/month
That's $540.00/year compared to Grok 4 Fast at your current usage level of 100K calls/month.
| Metric | Grok 4 Fast | Step 3.5 Flash (free) | Winner |
|---|---|---|---|
| Overall Score | 83 | 78 | Grok 4 Fast |
| Rank | #52 | #86 | Grok 4 Fast |
| Quality Rank | #52 | #86 | Grok 4 Fast |
| Adoption Rank | #52 | #86 | Grok 4 Fast |
| Parameters | -- | -- | -- |
| Context Window | 2000K | 256K | Grok 4 Fast |
| Pricing | $0.20/$0.50/M | Free | -- |
| Signal Scores | |||
| Capabilities | 100 | 50 | Grok 4 Fast |
| Benchmarks | 70 | -- | Grok 4 Fast |
| Pricing | 1 | 30 | Step 3.5 Flash (free) |
| Context window size | 100 | 86 | Grok 4 Fast |
| Recency | 99 | 100 | Step 3.5 Flash (free) |
| Output Capacity | 75 | 90 | Step 3.5 Flash (free) |
Our composite score (0–100) combines six weighted signals: benchmark performance (25%), pricing efficiency (25%), context window size (15%), model recency (15%), output capacity (10%), and capability versatility (10%). Here's what the scores mean for these two models:
Scores 83/100 (rank #52), placing it in the top 82% of all 290 models tracked.
Scores 78/100 (rank #86), placing it in the top 71% of all 290 models tracked.
Grok 4 Fast has a 5-point advantage, which typically translates to noticeably better performance on complex reasoning, code generation, and multi-step tasks.
Both models are priced similarly, so the decision comes down to quality and features rather than cost.
Both models have comparable response speeds. For most applications, the latency difference is negligible.
When latency matters most: Interactive chatbots, IDE code completion, real-time translation, and user-facing applications where response time directly impacts experience. For batch processing, background summarization, or offline analysis, latency is less critical.
Code generation & review
Higher benchmark score (0/100) indicates stronger performance on coding tasks like generating functions, debugging, and refactoring
Customer support chatbot
Faster response time (speed score 0/100) is critical for user-facing chat. Step 3.5 Flash (free) also offers lower per-token costs for high-volume support
Long document analysis
Larger context window (2000K tokens) can process longer documents, contracts, and research papers in a single pass
Batch data extraction
Lower output pricing ($0.00/M) reduces costs when processing thousands of records daily
Creative writing & content
Higher overall composite score (83/100) correlates with better nuance, coherence, and style in long-form content
Image understanding & OCR
Supports vision input - can analyze screenshots, diagrams, photos, and scanned documents directly
Grok 4 Fast has a moderate advantage with a 5.200000000000003-point lead in composite score. It wins on more signal dimensions, but Step 3.5 Flash (free) has specific strengths that could make it the better choice for certain workflows.
Best for Quality
Grok 4 Fast
Marginally better benchmark scores; both are excellent
Best for Cost
Step 3.5 Flash (free)
100% lower pricing; better value at scale
Best for Reliability
Grok 4 Fast
Higher uptime and faster response speeds
Best for Prototyping
Grok 4 Fast
Stronger community support and better developer experience
Best for Production
Grok 4 Fast
Wider enterprise adoption and proven at scale
by xAI
| Capability | Grok 4 Fast | Step 3.5 Flash (free) |
|---|---|---|
| Vision (Image Input)differs | ||
| Function Calling | ||
| Streaming | ||
| JSON Modediffers | ||
| Reasoning | ||
| Web Searchdiffers | ||
| Image Output |
xAI
StepFun
Step 3.5 Flash (free) saves you $0.9600/month
That's 100% cheaper than Grok 4 Fast at 1,000 tokens/request and 100 requests/day.
Assumes 60% input / 40% output token ratio per request. Actual costs may vary based on your usage pattern.
| Parameter | Grok 4 Fast | Step 3.5 Flash (free) |
|---|---|---|
| Context Window | 2M | 256K |
| Max Output Tokens | 30,000 | 256,000 |
| Open Source | No | Yes |
| Created | Sep 19, 2025 | Jan 29, 2026 |
Grok 4 Fast scores 83/100 (rank #52) compared to Step 3.5 Flash (free)'s 78/100 (rank #86), giving it a 5-point advantage. Grok 4 Fast is the stronger overall choice, though Step 3.5 Flash (free) may excel in specific areas like cost efficiency.
Grok 4 Fast is ranked #52 and Step 3.5 Flash (free) is ranked #86 out of 290+ AI models. Rankings use a composite score combining benchmark performance (25%), pricing (25%), context window (15%), recency (15%), output capacity (10%), and versatility (10%). Scores update hourly.
Step 3.5 Flash (free) is cheaper at $0.00/M output tokens vs Grok 4 Fast's $0.50/M output tokens - 500.0x more expensive. Input token pricing: Grok 4 Fast at $0.20/M vs Step 3.5 Flash (free) at $0.00/M.
Grok 4 Fast has a larger context window of 2,000,000 tokens compared to Step 3.5 Flash (free)'s 256,000 tokens. A larger context window means the model can process longer documents and conversations.