DeepSeek V3.1 vs GPT-5.5 Pro
DeepSeek V3.1 (2025) and GPT-5.5 Pro (2026) are frontier reasoning models from DeepSeek and OpenAI. DeepSeek V3.1 ships a 64k-token context window, while GPT-5.5 Pro ships a 1.05m-token context window. On SWE-bench Verified, GPT-5.5 Pro leads by 16.6 pts. On pricing, DeepSeek V3.1 costs $0.27/1M input tokens versus $30/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
DeepSeek V3.1 is ~11011% cheaper at $0.27/1M; pay for GPT-5.5 Pro only for coding workflow support.
Decision scorecard
Local evidence first| Signal | DeepSeek V3.1 | GPT-5.5 Pro |
|---|---|---|
| Best for | multimodal apps and provider-routed production | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | Coding, Agents, and Vision | Coding, RAG, and Agents |
| Context window | 64k | 1.05m |
| Cheapest output | $1/1M tokens | $180/1M tokens |
| Provider routes | 8 tracked | 3 tracked |
| Shared benchmarks | 1 shared | SWE-bench Verified leader |
Decision tradeoffs
- DeepSeek V3.1 has the lower cheapest tracked output price at $1/1M tokens.
- DeepSeek V3.1 has broader tracked provider coverage for fallback and route flexibility.
- Local decision data tags DeepSeek V3.1 for Coding, Agents, and Vision.
- GPT-5.5 Pro holds a shared-benchmark lead on SWE-bench Verified, ahead by 16.6 points.
- GPT-5.5 Pro has the larger context window for long prompts, retrieval packs, or transcript analysis.
- GPT-5.5 Pro uniquely exposes Reasoning and JSON / Tool use in local model data.
- Local decision data tags GPT-5.5 Pro for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
DeepSeek V3.1
$466
Cheapest tracked route/tier: Novita AI
GPT-5.5 Pro
$69,000
Cheapest tracked route/tier: OpenAI API <=272K tokens (standard)
Estimated monthly gap: $68,534. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on Vercel AI Gateway; start route-level A/B tests there.
- GPT-5.5 Pro is $179/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- GPT-5.5 Pro adds Reasoning and JSON / JSON / Tool use in local capability data.
- Provider overlap exists on Vercel AI Gateway; start route-level A/B tests there.
- DeepSeek V3.1 is $179/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Reasoning and JSON / JSON / Tool use before moving production traffic.
Specs
| Specification | ||
|---|---|---|
| Released | 2025-08-21 | 2026-04-23 |
| Context window | 64k | 1.05m |
| Parameters | 671B total, 37B active (MoE) | — |
| Architecture | Mixture of Experts | Decoder Only |
| License | MITOSI-approved | Proprietary |
| Openness | Open source | Proprietary |
| Weights | Unknown | Not released |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: permitted | Commercial use: conditional |
| Knowledge cutoff | - | 2025-12 |
Pricing and availability
| Pricing attribute | DeepSeek V3.1 | GPT-5.5 Pro |
|---|---|---|
| Input price | $0.27/1M tokens | $30/1M tokens |
| Output price | $1/1M tokens | $180/1M tokens |
| Providers |
Capabilities
| Capability | DeepSeek V3.1 | GPT-5.5 Pro |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | No | Yes |
| JSON / Tool use | No | Yes |
| Structured outputs | Yes | Yes |
| Code execution | Yes | Yes |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | DeepSeek V3.1 | GPT-5.5 Pro |
|---|---|---|
| SWE-bench Verified | 66.0 | 82.6 |
Continue comparing
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Last reviewed: 2026-06-29. Data sourced from public model cards and provider documentation.