ByteDance Seed: Seed 1.6 Flash

bytedance-seed/seed-1.6-flash · ByteDance SeedTokenizer lineage measured

Tokenizer group (measured): ByteDance Seed
Evidence confidence: Very high
Declared tokenizer tag: Other
Entered catalogue: 23 December 2025
Last tested: 21 August 2026
Measurement: Measured

Evidence

✓ exact tokenizer signature shared with 5 models
✓ API-surface contract identical to a group member

Compare with ByteDance Seed: Seed 2.1 Turbo

Download JSON Report a correction

Identity statement

ByteDance Seed: Seed 1.6 Flash is ByteDance Seed's model, and its measured tokenizer sits in ByteDance Seed's own signature group alongside its sibling models. No other maker's measured model shares it so far.

Evidence stack

Signals of different kinds, weighed together

Signal	Result	Reference
Tokenizer signature	Exact match with 5 other models	tk_25bf52d0
API surface	Identical contract to 1 other entry	api_1e32a0a1
Context and output	262,144 context · 32,768 max output	declared
Reasoning contract	Optional	declared
Serving providers observed	Seed	measured 21 August 2026

Shares this fingerprint

Exact signature first; template-boundary shifts of the same signature beneath

ByteDance Seed: Seed 1.6bytedance-seed/seed-1.6exact · 50/50 ByteDance Seed: Seed 2.1 Turbobytedance-seed/seed-2-1-turboexact · 50/50 ByteDance Seed: Seed-2.0-Codebytedance-seed/seed-2.0-codeexact · 50/50 ByteDance Seed: Seed-2.0-Litebytedance-seed/seed-2.0-liteexact · 50/50 ByteDance Seed: Seed-2.0-Minibytedance-seed/seed-2.0-miniexact · 50/50

Closest measured models

Agreement across the mutually clean test strings

ByteDance Seed: Seed-2.0-Minibytedance-seed/seed-2.0-mini50/50 · 100%ByteDance Seed: Seed 1.6bytedance-seed/seed-1.650/50 · 100%ByteDance Seed: Seed-2.0-Litebytedance-seed/seed-2.0-lite50/50 · 100%ByteDance Seed: Seed 2.1 Turbobytedance-seed/seed-2-1-turbo50/50 · 100%ByteDance Seed: Seed-2.0-Codebytedance-seed/seed-2.0-code50/50 · 100%Qwen: Qwen3.5 Plus 2026-04-20qwen/qwen3.5-plus-2026042013/27 · 48%

Click a row to open the full comparison.

The measured fingerprint

Marginal prompt-token cost of each test string, grouped by script

All 50 rows

English and whitespace

en-prose14

en-long16

spaces-203

spaces-603

tabs-204

newlines-204

mixed-ws7

Digits

digits-99

digits-1212

digits-3030

digits-sep12

float-long22

CJK

zh-common11

zh-long13

zh-rare18

ja-kana18

ja-kanji13

ko13

Other scripts

ru13

ar12

he13

hi17

th16

el14

Emoji

emoji-basic9

emoji-skin14

emoji-zwj-family11

emoji-zwj-x333

emoji-flags16

emoji-prof19

Rare Unicode

math30

boxdraw29

combining5

cjk-ext-b16

surrogates41

zalgo36

rtl-mix6

Code

py-code26

py-indent18

json25

html16

regex50

camel7

snake8

Repetition and encodings

rare-word-x531

repeat-tok41

base6433

hex19

url20

uuid36

An x marks a row excluded as corrupt (caching or provider interference detected during measurement). Overhead subtracted: 82 prompt tokens.

Declared record

What the catalogue claims about this model

Seed 1.6 Flash is an ultra-fast multimodal deep thinking model by ByteDance Seed, supporting both text and visual understanding. It features a 256k context window and can generate outputs of...

Modalities: text+image+video->text
Declared tokenizer: Other
Prompt price: $0.07 / M tokens
Completion price: $0.30 / M tokens

Supported parameters

frequency_penaltyinclude_reasoningmax_tokensreasoningresponse_formatstopstructured_outputstemperaturetool_choicetoolstop_p

defaults: {"temperature":null,"top_p":null,"frequency_penalty":null}

Catalogue entry

History

Every observation, kept as taken

23 December 2025Enters the OpenRouter catalogue with no declared family.
21 August 2026Fingerprinted in the YFarmX catalogue sweep · 50 of 50 strings measured clean.
21 August 2026YFarmX assessment: consistent with the ByteDance Seed family, very high confidence.

Cite this page as the evidence record for ByteDance Seed: Seed 1.6 Flash: the URL is stable, measurements are dated, and revisions append to the history above. Method: tokenizer fingerprinting, v1, 50 strings.