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DeepSeek V3.1 vs GPT OSS 120B

DeepSeek V3.1 grades higher overall (68.7 against 46.1). GPT OSS 120B costs 83% less for the same work.

DeepSeek V3.1

by DeepSeek · #31 of 67 overall

Coming soon · price at launch
Context
160K
Input / 1M
$0.25
Output / 1M
$0.95

GPT OSS 120B

by OpenAI · #53 of 67 overall

Coming soon · price at launch
Context
128K
Input / 1M
$0.037
Output / 1M
$0.17

Better overall

DeepSeek V3.1

Grade 68.7 vs 46.1

Cheaper

GPT OSS 120B

83% less, $0.070 vs $0.42 blended

Larger context

DeepSeek V3.1

160K vs 128K tokens

SWE-bench Verified

DeepSeek V3.1

66% vs 62.4%

Head to head

Public benchmarks. Longer is better; each value links to its source.

LMArena TextElo-style rating · LMArena (CC BY 4.0) · Oct 28, 2026
LMArena CodingElo-style rating · LMArena (CC BY 4.0) · Oct 28, 2026
Aider Polyglot% of exercises solved · Aider (aider.chat) · Aug 21, 2025
SWE-bench Verified% of issues resolved · SWE-bench · Aug 21, 2025 · reference
LiveCodeBenchpass@1, % · LiveCodeBench · Aug 21, 2025 · reference
GPT OSS 120BGPT OSS 120B: —

DeepSeek V3.1GPT OSS 120Bv = reported by the model’s maker. — = no public score yet. Arena bars span the range across every model we grade.

What it costs you

Drag to match your monthly usage.

DeepSeek V3.1$88.00 /month
GPT OSS 120B$14.20 /month

GPT OSS 120B saves you $73.80 a month at this usage, $886 a year.

At a glance

AttributeDeepSeek V3.1GPT OSS 120B
Made byDeepSeekOpenAI
AvailabilityComing soonComing soon
Overall gradeStrong · 68.7Good · 46.1
Overall rank#31 of 67#53 of 67
Input price$0.25 per 1M$0.037 per 1M
Output price$0.95 per 1M$0.17 per 1M
Context window163,840 tokens131,072 tokens
Reasoning levelsYesYes
Reads imagesNoNo
Model IDdeepseek-v3.1gpt-oss-120b

Try both with one key

Same endpoint, same key, both hosted in the USA. Change one word to switch models, in Claude Code, Cursor, Cline or your own code.

Get your API key
# Ask either model the same thing
curl https://fullsendai.com/v1/chat/completions \
  -H "Authorization: Bearer $FULLSEND_API_KEY" \
  -d '{"model": "deepseek-v3.1", "messages": [...]}'

# …then swap one word
  -d '{"model": "gpt-oss-120b", "messages": [...]}'

Questions

Is DeepSeek V3.1 or GPT OSS 120B better?

DeepSeek V3.1 grades 68.7 against 46.1 for GPT OSS 120B, from public benchmarks.

Which is cheaper, DeepSeek V3.1 or GPT OSS 120B?

GPT OSS 120B: $0.037 in and $0.17 out per million tokens, against $0.25 and $0.95 through FullsendAI.

Which has the larger context window?

DeepSeek V3.1, with 163,840 tokens.

Can I use both with one API key?

Yes, once they launch: both are coming soon, at the prices shown, and both will use the same FullsendAI key.

Model rankingsAll benchmarksCompare other models

Scores: LMArena (CC BY 4.0), Aider (aider.chat), SWE-bench, LiveCodeBench, and model makers’ published results where marked v. Prices are FullsendAI’s, per million tokens. Data as of Oct 28, 2026.