AI model comparison
Compare recorded price, context, output limits, speed, latency, capabilities, and input/output support. Every missing value stays visible, and unsourced benchmarks are excluded.
DeepSeek V4 Flash 0731 and Step 3.5 Flash both come up when teams are choosing a model for production work, and the honest answer usually depends on your workload rather than a leaderboard. This page puts their published specifications side by side — context window, token pricing, supported inputs and outputs — so you can see where they actually differ.
DeepSeek
Official DeepSeek V4 Flash release with enhanced agentic capabilities and integrated DSpark speculative decoding
Accepts
Produces
StepFun
StepFun flash lane for quick multimodal reasoning and coding assistance
Accepts
Produces
At a glance
This is a directional summary of the values recorded in this directory—not a universal quality verdict. Test the finalists on your own prompts before committing.
Where DeepSeek V4 Flash 0731 leads in recorded data
Where Step 3.5 Flash leads in recorded data
Context capacity
Higher listed limit
DeepSeek V4 Flash 0731:1M
Step 3.5 Flash:256K
DeepSeek V4 Flash 0731
Maximum output
Higher listed limit
DeepSeek V4 Flash 0731:384K
Step 3.5 Flash:256K
DeepSeek V4 Flash 0731
Input price
Lower recorded price
DeepSeek V4 Flash 0731:$0.16
Step 3.5 Flash:$0.10
Step 3.5 Flash
Output price
Lower recorded price
DeepSeek V4 Flash 0731:$0.40
Step 3.5 Flash:$0.30
Step 3.5 Flash
Output speed
Higher recorded throughput
DeepSeek V4 Flash 0731:—
Step 3.5 Flash:—
No complete comparison
Time to first token
Lower recorded latency
DeepSeek V4 Flash 0731:—
Step 3.5 Flash:—
No complete comparison
Intelligence Index
Higher directory index
DeepSeek V4 Flash 0731:—
Step 3.5 Flash:—
No complete comparison
Evidence
A score appears only when both records include a verified source. It is not treated as a universal ranking.
Specifications
| Specification | DeepSeek V4 Flash 0731 | Step 3.5 Flash |
|---|---|---|
| Provider | DeepSeek | StepFun |
| Model family | deepseek-flash | — |
| Accepted inputs | text | text |
| Produced outputs | text | text |
| Context window | 1MRecorded lead | 256K |
| Max output | 384KRecorded lead | 256K |
| Intelligence Index | — | — |
| Input price / 1M | $0.16 | $0.10Recorded lead |
| Output price / 1M | $0.40 | $0.30Recorded lead |
| Output speed | — | — |
| Time to first token | — | — |
| Reasoning mode | Documented | Documented |
| Tool calling | Documented | Documented |
| Image input | Not documented | Not documented |
| Audio input | Not documented | Not documented |
| Structured output | Documented | Not documented |
| License | Open weights | Open weights |
| Released | Jul 31, 2026 | Jan 29, 2026 |
Workload guidance
On the published numbers, DeepSeek V4 Flash 0731 accepts the larger context window and Step 3.5 Flash is cheaper per input token. Which matters more depends on whether your bottleneck is document size or spend — the table above has the exact figures.
Provenance
Prices and hosted performance can change. SyncDev records source references and clearly separates documented specifications from measured values; confirm commercial terms with the provider before deployment.
DeepSeek V4 Flash 0731
DeepSeek · model record and recorded source
Step 3.5 Flash
StepFun · model record and recorded source
Choose any two approved model records and review them with the same evidence rules.