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GPT-5.1-Codex vs DeepSeek V3.1

Detailed technical comparison between GPT-5.1-Codex (OpenAI) and DeepSeek V3.1 (DeepSeek). Review live API token pricing, context window capabilities, time-to-first-token latency, and verified benchmark scores side-by-side.

⚡ Executive Summary & Verdict

Comparison Snapshot

GPT-5.1-Codex: 6 WinsvsDeepSeek V3.1: 0 Wins
Context Leader

GPT-5.1-Codex

400,000 tokens
Agentic Tool-Calling

Tie

Equal Capability
Lowest Latency (TTFT)

Tie

Equal Speed
Input Price Leader

DeepSeek V3.1

$0.25 / MTok
OpenAIactive

GPT-5.1-Codex

GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks....

View GPT-5.1-Codex Full Specs →
DeepSeekactive

DeepSeek V3.1

DeepSeek-V3.1 is a large hybrid reasoning model (671B parameters, 37B active) that supports both thinking and non-thinking modes via prompt templates. It extends the DeepSeek-V3 base with a two-phase long-context...

View DeepSeek V3.1 Full Specs →

Technical Specifications

🏆 = Superior Spec
SpecificationGPT-5.1-CodexDeepSeek V3.1
ProviderOpenAIDeepSeek
Context Window400,000 tokens🏆163,840 tokens
Agent SuitabilityNot yet benchmarkedNot yet benchmarked
Time to First Token (TTFT)No public TTFT dataNo public TTFT data
Deployment Modelmanaged apiself hostable
Production StabilityStable GA (est.)Stable GA (est.)
API AvailableYesYes
Released Date2025-11-132025-08-21

API Pricing Comparison

Input Price per Million Tokens

GPT-5.1-Codex

$1.25

DeepSeek V3.1

$0.25

Output Price per Million Tokens

GPT-5.1-Codex

$10.00

DeepSeek V3.1

$0.95

💡 Cost Ratio: DeepSeek V3.1 is 5.0x cheaper per input token than GPT-5.1-Codex.

Want to test both models live?

Run side-by-side prompt benchmarks in our dynamic multi-model Sandbox. Compare execution speeds, latency metrics, and compute actual costs in real-time.

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Benchmark Performance Metrics

Standardized Scores (0–100%)

Scores show verified raw accuracy percentages across standardized AI evaluation suites. Higher bars indicate superior performance in that domain.

MMLUGeneral knowledge & multi-task understanding
92.8%vs80.0%+12.8% GPT-5.1-Codex
GPT-5.1-Codex 🏆
DeepSeek V3.1
HumanEvalPython coding & logic synthesis
99.0%vs78.2%+20.8% GPT-5.1-Codex
GPT-5.1-Codex 🏆
DeepSeek V3.1
MATHComplex mathematical problem solving
81.2%vs55.4%+25.8% GPT-5.1-Codex
GPT-5.1-Codex 🏆
DeepSeek V3.1
GPQAGraduate-level expert reasoning
59.6%vs40.8%+18.8% GPT-5.1-Codex
GPT-5.1-Codex 🏆
DeepSeek V3.1
HellaSwagCommonsense reasoning and inference
88.4%vs83.0%+5.4% GPT-5.1-Codex
GPT-5.1-Codex 🏆
DeepSeek V3.1
MT-BenchMulti-turn conversation flow quality
9.4%vs8.6%+0.9% GPT-5.1-Codex
GPT-5.1-Codex 🏆
DeepSeek V3.1

GPT-5.1-Codex Quirks & Gotchas

No developer gotchas reported.

DeepSeek V3.1 Quirks & Gotchas

No developer gotchas reported.

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