AI Desk · AI Fingerprinting · Compare
DeepSeek: DeepSeek V4.1 Flash · StepFun: Step 3.7 Flash
Identity similarity: highExact tokenizer agreement · 50/50Exact agreement across every measured string is one strong signal of shared tokenizer lineage. The published settings differ, so the second signal the methodology needs for very high is absent here; the table below shows where they part.
DeepSeek: DeepSeek V4.1 Flash recordStepFun: Step 3.7 Flash recordOpen in the interactive bench
Tokenizer fingerprint
50 of 50 mutually clean strings agree| Test string | DeepSeek: DeepSeek V4.1 Flash | StepFun: Step 3.7 Flash | Verdict |
|---|---|---|---|
| en-prose | 14 | 14 | match |
| en-long | 16 | 16 | match |
| spaces-20 | 3 | 3 | match |
| spaces-60 | 3 | 3 | match |
| tabs-20 | 4 | 4 | match |
| newlines-20 | 4 | 4 | match |
| mixed-ws | 7 | 7 | match |
| digits-9 | 3 | 3 | match |
| digits-12 | 4 | 4 | match |
| digits-30 | 10 | 10 | match |
| digits-sep | 7 | 7 | match |
| float-long | 9 | 9 | match |
| zh-common | 9 | 9 | match |
| zh-long | 10 | 10 | match |
| zh-rare | 18 | 18 | match |
| ja-kana | 9 | 9 | match |
| ja-kanji | 11 | 11 | match |
| ko | 13 | 13 | match |
| ru | 13 | 13 | match |
| ar | 10 | 10 | match |
| he | 14 | 14 | match |
| hi | 18 | 18 | match |
| th | 11 | 11 | match |
| el | 16 | 16 | match |
| emoji-basic | 10 | 10 | match |
| emoji-skin | 14 | 14 | match |
| emoji-zwj-family | 11 | 11 | match |
| emoji-zwj-x3 | 33 | 33 | match |
| emoji-flags | 16 | 16 | match |
| emoji-prof | 19 | 19 | match |
| math | 22 | 22 | match |
| boxdraw | 27 | 27 | match |
| combining | 10 | 10 | match |
| cjk-ext-b | 16 | 16 | match |
| surrogates | 33 | 33 | match |
| zalgo | 36 | 36 | match |
| rtl-mix | 6 | 6 | match |
| py-code | 25 | 25 | match |
| py-indent | 15 | 15 | match |
| json | 20 | 20 | match |
| html | 16 | 16 | match |
| regex | 47 | 47 | match |
| camel | 7 | 7 | match |
| snake | 8 | 8 | match |
| rare-word-x5 | 26 | 26 | match |
| repeat-tok | 41 | 41 | match |
| base64 | 34 | 34 | match |
| hex | 12 | 12 | match |
| url | 17 | 17 | match |
| uuid | 27 | 27 | match |
Values are the marginal prompt-token cost of each string with the model's fixed overhead subtracted. An x marks a row excluded as corrupt for that model.
API surface
The declared serving contracts differ| Field | DeepSeek: DeepSeek V4.1 Flash | StepFun: Step 3.7 Flash | Verdict |
|---|---|---|---|
| Context length | 1048576 | 262144 | × differs |
| Max output tokens | – | 230400 | × differs |
| Supported parameters | frequency_penalty, include_reasoning, logit_bias, logprobs, max_tokens, min_p, presence_penalty, reasoning, reasoning_effort, repetition_penalty, response_format, seed, stop, structured_outputs, temperature, tool_choice, tools, top_k, top_logprobs, top_p | frequency_penalty, include_reasoning, logprobs, max_tokens, presence_penalty, reasoning, reasoning_effort, repetition_penalty, response_format, seed, stop, structured_outputs, temperature, tool_choice, tools, top_k, top_logprobs, top_p | × differs |
| Defaults | {} | {"temperature":null,"top_p":null,"top_k":null,"frequency_penalty":null,"presence_penalty":null,"repetition_penalty":null} | × differs |
| Reasoning contract | {"mandatory":false,"default_enabled":true,"supported_efforts":["max","high","low"],"default_effort":"high"} | {"mandatory":true,"supported_efforts":["high","medium","low"],"default_effort":"medium"} | × differs |
| Modalities | text+image->text | text+image+video->text | × differs |
DeepSeek: DeepSeek V4.1 Flash: OpenRouter's listing shows 943,718 output tokens, which is 90% of the context window, the figure it carries where the provider declares no maximum. DeepSeek's own API reference caps max_tokens at 384K, 393,216 tokens, for deepseek-flash and deepseek-v4-pro.
Method: tokenizer fingerprinting, v1, 50 strings. This page is static and dated; the interactive bench compares any two of the 337 measured models.