Side-by-side comparison of pricing, context window, benchmarks, capabilities, and license. Data sourced from the Interestana AI Index, kept current as developers update their models.
Model A — DeepSeek
DeepSeek V3.5 is a mixture-of-experts model with 685B total parameters and 37B activated per token. Notable for delivering frontier performance at a fraction of the training cost of competing models.
Model B — OpenAI
o3 is OpenAI’s flagship reasoning model, scaling deliberate test-time compute to solve novel mathematics and science problems that earlier LLMs could not.
| Property | DeepSeek V3.5 | OpenAI o3 |
|---|---|---|
| Released | Mar 24, 2026 | Jan 31, 2026 |
| Developer | DeepSeek | OpenAI |
| Type | llm | reasoning |
| License | open-weight | proprietary |
| Context window | 128,000 | 200,000 |
| Parameters | 685B MoE (37B active) | undisclosed |
| Input $/M tokens | $0.27 | $15.00 |
| Output $/M tokens | $1.10 | $60.00 |
Bold green values indicate the winner on that dimension where comparison is meaningful (lower price wins; bigger context wins; more open license wins; newer date wins).
Programmatic access available at /api/ai/compare?a=deepseek-v3-5&b=o3. CORS is open. Citation guidance: /about/editorial-process.