GPT-5.5 Pro
OpenAI's highest-intelligence frontier model with extended test-time compute, multimodal reasoning, and a 1M-token context window for deep research and agentic work.
Get API key- Provider
- OpenAI
- Price
- $37.50 in · $225 out / 1M
- Context window
- 1M tokens
- Released
- April 23, 2026
- License
- Proprietary
What is GPT-5.5 Pro?
GPT-5.5 Pro is OpenAI's highest-intelligence frontier model, released in April 2026. It uses the same base as GPT-5.5 with extended parallel test-time compute for deep reasoning, research, coding, and complex agentic tasks. It supports vision, function calling, web search, and structured output across a 1M-token context window with up to 128K output.
Use it privately on Venice
On Venice, GPT-5.5 Pro runs under an anonymized privacy tier with zero retention — your prompts are not stored, profiled, or used for training. You get OpenAI's highest-intelligence frontier model with vision, reasoning, web search, and tool use, minus the Big-Tech surveillance baggage. Pay per token with no subscription lock-in, giving permissionless access to frontier intelligence.
What can it do?
- •Massive 1M-token context window with strong long-context retrieval, making it ideal for whole-codebase reasoning and multi-document analysis.
- •Top-tier agentic capabilities — it plans, uses tools, checks its work, and persists through ambiguous multi-step coding, research, and data tasks.
- •Built-in vision, web search, function calling, and structured JSON output for multimodal, grounded workflows.
- •Extended test-time compute delivers OpenAI’s highest reasoning quality for hard math, science, and research-grade synthesis.
- •Efficient token usage on coding tasks — completes the same Codex work with significantly fewer tokens than prior generations.
- •Extremely high output pricing — at $225 per 1M output tokens on Venice, it can wreck a budget on long generations.
- •Closed and proprietary — no open weights, so self-hosting or fine-tuning is impossible.
- •Trimmed tool surface versus base GPT-5.5 — lacks apply_patch, skills, computer use, and tool search.
- •No streaming support — long Pro requests run in background mode, which can slow interactive workflows.
- •Carries OpenAI’s strongest safeguards to date; while reducing misuse, this may restrict certain edge or controversial prompts that uncensored models allow.
- •Slower time-to-first-token on deep-reasoning queries, trading latency for higher answer quality.
GPT-5.5 Pro capabilities
- Tool use / function calling
- Vision (image input)
- Reasoning
- Web search
- Code-optimized
- Structured output (JSON schema)
- Audio input
- Video input
- Multiple image inputs
- Log probabilities
How to use it via API
Venice exposes an OpenAI-compatible API. Swap your base URL and call openai-gpt-55-pro.
curl https://api.venice.ai/api/v1/chat/completions \
-H "Authorization: Bearer $VENICE_API_KEY" \
-H "Content-Type: application/json" \
-d '{
"model": "openai-gpt-55-pro",
"messages": [{ "role": "user", "content": "Explain quantum tunneling simply." }]
}'Specifications
Pricing
Billed per token on Venice: $37.50 per 1M input tokens and $225 per 1M output tokens.
New Venice accounts include a free daily allowance and 500 welcome credits — no credit card required.
GPT-5.5 Pro vs alternatives
| Model | Context window | Best for | Open weights | Price (Venice) |
|---|---|---|---|---|
| GPT-5.5 Pro | 1M tokens | Deep reasoning & research | No | $37.50 in · $225 out / 1M |
| Claude Opus 4.8 | 1M tokens | Writing & long-form prose | No | $6 in · $30 out / 1M |
| Grok 4.3 | 1M tokens | Real-time web & edgy queries | No | $1.42 in · $2.83 out / 1M |
| DeepSeek V3.2 | 160K tokens | Cheap open-weight coding | Yes | $0.33 in · $0.48 out / 1M |
The highest-intelligence tier in the GPT-5.5 family, trading cost for reasoning depth and a 1M context window.
What is it good for?
- •Deep research and scientific synthesis where extended reasoning beats fast answers.
- •Agentic coding across large repositories and multi-file software engineering.
- •Multimodal knowledge work — analyzing documents, spreadsheets, and images together.
- •High-stakes math, logic, and competitive programming requiring step-by-step verification.
- •Long-context document analysis and legal/financial review over hundreds of pages.
Prompting tips
- •Break complex tasks into explicit sub-goals — the model plans better when it sees the full roadmap.
- •Use JSON schema mode for structured extraction from long documents to control verbose outputs.
- •For coding, provide repository context or file trees; the model excels at whole-codebase reasoning.
- •Be explicit about ambiguity — GPT-5.5 Pro checks its work, but clear constraints reduce unnecessary reasoning loops.
- •Gate long outputs carefully: at $225 per 1M output tokens, concise prompts and tight max-token limits protect your budget.
Version history
Base flagship model with adjustable reasoning effort.
CurrentCurrent — Pro tier with parallel test-time compute for maximum reasoning depth.
Frequently asked questions
GPT-5.5 Pro is OpenAI's highest-intelligence frontier model, released in April 2026. It uses the same base as GPT-5.5 with extended parallel test-time compute for deep reasoning, research, coding, and complex agentic tasks, supporting vision, web search, and tool use across a 1M-token context window.
On Venice, GPT-5.5 Pro is billed at $37.50 per 1 million input tokens and $225 per 1 million output tokens. There is no subscription required; you pay per token with credits.
No. GPT-5.5 Pro is closed and proprietary to OpenAI, with no open weights available. If you need an open-weights alternative, DeepSeek V3.2 or Kimi K2.6 on Venice are the closest options.
Yes. On Venice, GPT-5.5 Pro supports function calling, vision (image input), web search, structured JSON output, and multiple image inputs. It is designed for agentic workflows that combine tools and multimodal reasoning.
Choose GPT-5.5 Pro for deep reasoning, agentic coding, and long-context retrieval over 1M tokens. Choose Claude Opus 4.8 for long-form writing, nuanced prose, and a significantly lower per-token cost.
Its training data extends through December 2025, so it may not know about events after that date unless you use its built-in web search capability.
No — OpenAI disables streaming on the Pro tier. Long requests run in background mode to avoid client timeouts, which makes it better suited for batch research than interactive chat.
No. Venice runs the model as-is, which includes OpenAI's strongest safeguards to date. Your prompts remain private and are not stored, but the model itself will refuse certain harmful or edge requests per OpenAI's safety policy.
Related models
Run GPT-5.5 Pro privately.
No prompt logging. No data used for training. Free to start — no credit card.
