Side-by-side technical and economic comparison between OpenAI's GPT-5.6 Terra and DeepSeek's DeepSeek-V3 (Legacy API Alias).
• DeepSeek-V3 (Legacy API Alias): Classified as a Legacy Reference model (Legacy Reference (API Aliased)).
| Metric | GPT-5.6 Terra | DeepSeek-V3 (Legacy API Alias) | Advantage |
|---|---|---|---|
| Provider Organization | OpenAI | DeepSeek | — |
| Standard Input / 1M | $2.00 | $0.14 | DeepSeek-V3 (Legacy API Alias) (93% lower) |
| Cached Input / 1M | $0.20 | $0.014 | DeepSeek-V3 (Legacy API Alias) lower |
| Output / 1M | $12.00 | $0.28 | DeepSeek-V3 (Legacy API Alias) lower |
| Context Window | 1.05M | 128k | GPT-5.6 Terra (1.05M) |
| Max Generation Tokens | 16.4k | 8.2k | GPT-5.6 Terra |
| Tokenizer Family | OpenAI o200k_base (200k vocabulary) | DeepSeek Byte-level BPE (~128k vocabulary) | — |
Opt for GPT-5.6 Terra when your engineering requirements prioritize OpenAI's ecosystem, specific tokenizer efficiencies (Exact BPE (o200k_base)), or when your expected prompt-to-completion ratios favor its $2/M input rate.
Opt for DeepSeek-V3 (Legacy API Alias) when looking for DeepSeek's tooling integration, specific context window depth (128k tokens), or when output generation volume favors its $0.28/M rate.