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GPT-5.3 Codex vs Seed 2.1 Turbo

GPT-5.3 Codex and Seed 2.1 Turbo are closely matched at 36.4 and 43.0 on the LLM Stats Score.

OpenAI · ByteDance · Updated for 2026

Which is better?

GPT-5.3 Codex and Seed 2.1 Turbo are closely matched on the overall LLM Stats Score at 36.4 and 43.0.

In the 1 individual benchmarks reported for both models, Seed 2.1 Turbo wins 1; this is a narrower head-to-head signal than the composite indexes.

Based on current LLM Stats indexes, shared benchmarks, pricing, and model metadata for 2026.

Choose GPT-5.3 Codex

  • you want predictable pricing at $1.75/M input and $14.00/M output

Choose Seed 2.1 Turbo

  • you value its reported benchmark strengths — it wins 1 of 1 exact shared results
  • you want the most recent training data — it shipped Jun 2026

At a glance

The differences that matter most.

GPT-5.3 Codex
OpenAI
Seed 2.1 Turbo
ByteDance
Core performance indexes
LLM Stats Score
36.4
#84
43.0
#48
Reasoning
37.0
#77
44.4
#37
Coding
29.7
#59
30.5
#53
Agents
22.5
#66
28.9
#44
Cost, coverage & limits
Benchmark wins
0 of 1
1 of 1
Input price
$1.75 / M
— / M
Output price
$14.00 / M
— / M
Context window
400,000
—

Individual benchmarks

6 reported for GPT-5.3 Codex · 90 for Seed 2.1 Turbo

1 shared

GPT-5.3 Codex outperforms in 0 benchmarks, while Seed 2.1 Turbo is better at 1 benchmark (SWE-Bench Pro).

Seed 2.1 Turbo significantly outperforms across most benchmarks.

Fri Oct 02 2026 • llm-stats.com

Human preference

Blind head-to-head votes and playground preference scores

Context Window

Maximum input and output token capacity

Only GPT-5.3 Codex specifies input context (400,000 tokens). Only GPT-5.3 Codex specifies output context (128,000 tokens).

OpenAI
GPT-5.3 Codex
Input400,000 tokens
Output128,000 tokens
ByteDance
Seed 2.1 Turbo
Input- tokens
Output- tokens
Fri Oct 02 2026 • llm-stats.com

Input capabilities

Documented input modalities across available providers

Both GPT-5.3 Codex and Seed 2.1 Turbo support multimodal inputs.

They are both capable of processing various types of data, offering versatility in application.

GPT-5.3 Codex

Text
Images
Audio
Video

Seed 2.1 Turbo

Text
Images
Audio
Video

License

Usage and distribution terms

Both models are licensed under proprietary licenses.

Both models have usage restrictions defined by their respective organizations.

GPT-5.3 Codex

Proprietary

Closed source

Seed 2.1 Turbo

Proprietary

Closed source

Release Timeline

When each model was launched

GPT-5.3 Codex was released on 2026-02-05, while Seed 2.1 Turbo was released on 2026-06-24.

Seed 2.1 Turbo is 5 months newer than GPT-5.3 Codex.

GPT-5.3 Codex

Feb 5, 2026

7 months ago

Seed 2.1 Turbo

Jun 24, 2026

3 months ago

4mo newer

Knowledge Cutoff

When training data ends

Neither model specifies a knowledge cutoff date.

Unable to compare the recency of their training data.

No cutoff dates available

Outputs Comparison

Notice missing or incorrect data?

Judge for yourself.

Run your own prompts against GPT-5.3 Codex and Seed 2.1 Turbo side-by-side, then vote on the output you prefer.

GPT-5.3 Codex
✓ Preferred
Seed 2.1 Turbo
Open in Playground

FAQ

Common questions about GPT-5.3 Codex vs Seed 2.1 Turbo.

Which is better, GPT-5.3 Codex or Seed 2.1 Turbo?

GPT-5.3 Codex and Seed 2.1 Turbo are closely matched on the LLM Stats Score at 36.4 and 43.0. GPT-5.3 Codex is made by OpenAI and Seed 2.1 Turbo is made by ByteDance. The best choice depends on your use case — compare their capability indexes, individual benchmarks, pricing, and limits above.

How does GPT-5.3 Codex compare to Seed 2.1 Turbo in benchmarks?

GPT-5.3 Codex scores SWE-Lancer (IC-Diamond subset): 81.4%, Cybersecurity CTFs: 77.6%, Terminal-Bench 2.0: 77.3%, LiveBench: 72.8%, OSWorld-Verified: 64.7%. Seed 2.1 Turbo scores CharXiv-D: 94.6%, MathVision: 92.7%, MathVista: 90.5%, MathVerse: 89.2%, Video-MME: 89.0%.

What are the context window sizes for GPT-5.3 Codex and Seed 2.1 Turbo?

GPT-5.3 Codex supports 400K tokens and Seed 2.1 Turbo supports an unknown number of tokens. A larger context window lets you process longer documents, conversations, or codebases in a single request.

What are the main differences between GPT-5.3 Codex and Seed 2.1 Turbo?

Key differences include LLM Stats Score (36.4 vs 43.0). See the full comparison above for benchmark-by-benchmark results.

Who makes GPT-5.3 Codex and Seed 2.1 Turbo?

GPT-5.3 Codex is developed by OpenAI and Seed 2.1 Turbo is developed by ByteDance.

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