GPT-5.3-Codex vs Step 5 Preview
Detailed technical comparison between GPT-5.3-Codex (OpenAI) and Step 5 Preview (StepFun). Review live API token pricing, context window capabilities, time-to-first-token latency, and verified benchmark scores side-by-side.
Comparison Snapshot
Step 5 Preview
1,000,000 tokensTie
Equal CapabilityTie
Equal SpeedStep 5 Preview
$1.00 / MTokGPT-5.3-Codex
GPT-5.3-Codex is an advanced artificial intelligence model engineered by OpenAI. Tailored for complex multi-step reasoning, programming synthesis, and extended document comprehension, GPT-5.3-Codex represents a key architectural iteration in the OpenAI model family. First released in 2026-02-24, it serves enterprise developers, research teams, and autonomous system architects requiring strict instruction compliance. Featuring an input capacity of 400,000 tokens (approximately 533 words), GPT-5.3-Codex processes multi-file code repositories, lengthy technical reports, and complex prompts in a single inference call.
Step 5 Preview
Step 5 Preview is an advanced artificial intelligence model engineered by StepFun. Tailored for complex multi-step reasoning, programming synthesis, and extended document comprehension, Step 5 Preview represents a key architectural iteration in the StepFun model family. First released in 2026-10-08, it serves enterprise developers, research teams, and autonomous system architects requiring strict instruction compliance. Featuring an input capacity of 1,000,000 tokens (approximately 1,333 words), Step 5 Preview processes multi-file code repositories, lengthy technical reports, and complex prompts in a single inference call.
Technical Specifications
🏆 = Superior Spec| Specification | GPT-5.3-Codex | Step 5 Preview |
|---|---|---|
| Provider | OpenAI | StepFun |
| Context Window | 400,000 tokens | 1,000,000 tokens🏆 |
| Agent Suitability | Not yet benchmarked | Not yet benchmarked |
| Time to First Token (TTFT) | No public TTFT data | No public TTFT data |
| Deployment Model | managed api | managed api |
| Production Stability | Stable GA (est.) | Beta Access (est.) |
| API Available | Yes | Yes |
| Released Date | 2026-02-24 | 2026-10-08 |
API Pricing Comparison
Input Price per Million Tokens
GPT-5.3-Codex
$1.75
Step 5 Preview
$1.00
Output Price per Million Tokens
GPT-5.3-Codex
$14.00
Step 5 Preview
$2.70
💡 Cost Ratio: Step 5 Preview is 1.8x cheaper per input token than GPT-5.3-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.
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.
GPT-5.3-Codex Quirks & Gotchas
No developer gotchas reported.
Step 5 Preview Quirks & Gotchas
No developer gotchas reported.
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