DeepSeek V3 vs GPT-5.5
2026 - Pricing, benchmarks, and use case comparison
Quick take
- •GPT-5.5 is open-weights - free to self-host with no API costs. DeepSeek V3 requires paid API access.
- •DeepSeek V3 is open-source: fine-tune it, self-host it, or use any inference provider. GPT-5.5 is closed-source.
Specs comparison
| DeepSeek V3 | GPT-5.5 | |
|---|---|---|
| Provider | DeepSeek | OpenAI |
| Type | Open source | Closed source |
| Context window | 128K | 128K |
| Input / 1M tokens | $0.27 | ✓Free (self-host) |
| Output / 1M tokens | $1.10 | Free (self-host) |
| Release date | 2024-12 | 2026-04 |
Benchmarks
| Benchmark | DeepSeek V3 | GPT-5.5 |
|---|---|---|
| HumanEval | 90.2% | - |
| MMLU | 88.5% | - |
| Aider Polyglot | 55.0% | - |
Scores sourced from official provider release posts.
Strengths
DeepSeek V3
- ✓Near-GPT-4o quality at a fraction of the price
- ✓Open weights - self-host or fine-tune freely
- ✓Efficient MoE architecture reduces inference cost
- ✓Strong coding (Aider polyglot, HumanEval)
- ✓Good instruction following and structured output
GPT-5.5
- ✓Improved instruction following over GPT-4o
- ✓Stronger long-context coherence
- ✓Better output consistency for agentic pipelines
- ✓GPT-5.5 Pro tier for reliability-critical workloads
- ✓Easier migration path than jumping from GPT-4o to GPT-5
Which should you choose?
Choose DeepSeek V3 if you need...
- →Cost-sensitive high-volume inference
- →Self-hosted deployments
- →Fine-tuning for specialized domains
- →Coding assistants
Choose GPT-5.5 if you need...
- →Production API integrations migrating from GPT-4o
- →Agentic workflows needing consistent structured output
- →Long-context document tasks
- →Teams deferring full GPT-5 migration costs