Seed 2.1 Pro vs GPT-5.5
Model Markets Rankings
Intelligence, Cost, and Efficiency
| Ranking | Seed 2.1 Pro | GPT-5.5 |
|---|---|---|
| IntelligenceHigher is better · MM Intelligence v1.2 | UnrankedNot in the 22-model eligible cohort | #5 of 2284.2 score |
| CostLower is better · Published-token output estimate | UnrankedNot in the 36-model eligible cohort | #32 of 36$0.341 per LiveBench case |
| EfficiencyHigher is better · MM Efficiency v1.0 | UnrankedNot in the 22-model eligible cohort | #10 of 2252.7 score |
Ranks come from the current complete eligible cohorts. Green highlights appear only when both models are ranked in the same metric. Missing required inputs remain unranked, and the three dimensions are not collapsed into an overall winner.
Benchmark Performance
Available Benchmarks
Technical Differences
Side-by-Side Facts
| Field | Seed 2.1 Pro | GPT-5.5 |
|---|---|---|
| Developer | ByteDance Seed | OpenAI |
| Family | Seed 2 1 | Gpt 5 5 |
| Model | Seed 2.1 Pro | GPT-5.5 |
| Version | Seed 2.1 Pro | GPT-5.5 |
| Lifecycle | active | active |
| Released | 2026-06-23 | 2026-04-23 |
| Knowledge cutoff | Unknown | 2025-12-01 |
| Input modalities | Text, Image, Video | Text, Image |
| Output modalities | Text | Text |
| Context window | Unknown | 1,050K |
| Total parameters | Unknown | Unknown |
| Active parameters | Unknown | Unknown |
| License | Unknown | Unknown |
| Open weights | No | No |
| API available | Yes | Yes |
| Self-hostable | No | No |
| Provider access | Unknown | Openai (Standard), Openrouter (Standard) |
| Capabilities | agents, chat, computer-use, generation, reasoning, structured_outputs, tools | chat, generation, reasoning, structured_outputs, tools |
12 comparable fields · 7 material differences · Pair passes the primary-source comparison gate
Seed 2.1 Pro Capabilities
GPT-5.5 Capabilities
Internal Comparison Graph
Related Comparisons
| A | Pair | B | Context |
|---|---|---|---|
Seed 2.1 ProByteDance Seed | vs | GPT-6 AstraOpenAI | cross-developer peersimage, text |
Claude Fable 5.1Anthropic | vs | Seed 2.1 ProByteDance Seed | cross-developer peersimage, text |
Seed 2.1 ProByteDance Seed | vs |  Gemini 3.1 ProGoogle DeepMind | cross-developer peerstext |
Seed 2.1 ProByteDance Seed | vs |  DeepSeek-V4-ProDeepSeek | cross-developer peerstext |
Seed 2.1 ProByteDance Seed | vs | Grok 4.6xAI | cross-developer peersimage, text |
Seed 2.1 ProByteDance Seed | vs |  Qwen3.8-MaxQwen | cross-developer peersimage, text, video |
Seed 2.1 ProByteDance Seed | vs |  Kimi-K3Moonshot AI | cross-developer peersimage, text |
 MiniMax-M3MiniMax | vs | Seed 2.1 ProByteDance Seed | cross-developer peersimage, text |
Seed 2.1 ProByteDance Seed | vs |  GLM-5.3Z.ai | cross-developer peerstext |
Seed 2.1 ProByteDance Seed | vs |  Hy4 previewTencent | cross-developer peerstext |
Seed 2.1 ProByteDance Seed | vs |  Mistral Large 3Mistral AI | cross-developer peersimage, text |
Seed 2.1 ProByteDance Seed | vs | cross-developer peersimage, text |
Primary Evidence
Sources and Freshness
Questions
Seed 2.1 Pro vs GPT-5.5 FAQs
Is Seed 2.1 Pro or GPT-5.5 better for coding?+
This comparison does not currently contain a protocol-matched coding benchmark for both Seed 2.1 Pro and GPT-5.5, so Model Markets cannot name a coding leader from pricing, context size, or capability labels alone.
Which is cheaper, Seed 2.1 Pro or GPT-5.5?+
Only GPT-5.5 has a directly sourced input price: $5.00 per million tokens. Only GPT-5.5 has a directly sourced output price: $30.00 per million tokens.
Which has a larger context window, Seed 2.1 Pro or GPT-5.5?+
Neither model has a larger sourced context window in this comparison. Seed 2.1 Pro is — and GPT-5.5 is 1,050K.
Which performs better in benchmarks, Seed 2.1 Pro or GPT-5.5?+
There is no overall benchmark winner: At least two independently verified, protocol-matched benchmarks are required for an overall winner.
Can Seed 2.1 Pro or GPT-5.5 be self-hosted?+
Both models have the same recorded self-hosting status: unsupported. Seed 2.1 Pro is not marked open weight; GPT-5.5 is not marked open weight.
Can Seed 2.1 Pro and GPT-5.5 understand images?+
Seed 2.1 Pro is documented with image input; GPT-5.5 is documented with image input. This reflects supported input modalities, not vision quality.
Which can generate longer answers, Seed 2.1 Pro or GPT-5.5?+
Neither has a larger sourced maximum output. Seed 2.1 Pro is — and GPT-5.5 is 128K.
Do Seed 2.1 Pro and GPT-5.5 support reasoning and tool use?+
Seed 2.1 Pro: reasoning, tool calling, and image input. GPT-5.5: reasoning, tool calling, and image input. Feature support does not establish relative quality.
Which is available from more inference providers, Seed 2.1 Pro or GPT-5.5?+
Seed 2.1 Pro has 0 sourced provider routes; GPT-5.5 has 2, so GPT-5.5 has broader tracked availability.
Which offers better value, Seed 2.1 Pro or GPT-5.5?+
There is no universal value winner. Compare the input and output prices above with the matched benchmark result for your workload: cheaper tokens can be offset by different quality, token usage, latency, or provider availability.