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OpenAI: GPT-5.1

GPT-5.1 is the latest frontier-grade model in the GPT-5 series, offering stronger general-purpose reasoning, improved instruction adherence, and a more natural conversational style compared to GPT-5. It uses adaptive reasoning...

Anyone in the Space can @-mention OpenAI: GPT-5.1 with the team's shared context - pooled credits, one chat, one memory.

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Verdict

GPT-5.1 delivers OpenAI's largest context window yet at 400K tokens, making it the go-to for processing entire codebases or multi-document analysis in a single pass. The $1.25/$10 pricing sits between o1 and GPT-4o, positioning it as a mid-tier option for teams that need deep context but not reasoning-heavy tasks. Reach for this when your workflow involves ingesting massive files or cross-referencing dozens of documents simultaneously, and you can tolerate higher output costs than GPT-4o.

Best for

  • Processing entire codebases in one context
  • Multi-document legal or research analysis
  • Long-form content generation with deep reference material
  • Technical documentation synthesis across repositories
  • Cost-effective alternative to o1 for context-heavy tasks

Strengths

The 400K token window is the standout feature, letting you load full repositories, lengthy PDFs, or dozens of reference documents without chunking or retrieval hacks. Input pricing at $1.25/Mtok undercuts o1 by 75%, making it viable for high-volume ingestion workflows. Multimodal support means you can mix screenshots, diagrams, and text in the same context. For teams that hit context limits on GPT-4o (128K) or find o1 overkill for non-reasoning tasks, this slots in as the practical middle ground.

Trade-offs

Output pricing at $10/Mtok is double GPT-4o's rate, so long-form generation gets expensive fast. Without public benchmarks, we lack hard data on reasoning depth or coding accuracy relative to o1 or Claude Sonnet 4.5. The model likely trades some per-token intelligence for that massive context window, so expect it to lag behind o1 on complex multi-step reasoning or nuanced instruction-following. Teams doing heavy generation or needing top-tier code quality may find GPT-4o or Claude more cost-effective despite smaller windows.

Specifications

Provider
openai
Category
llm
Context length
400,000 tokens
Max output
128,000 tokens
Modalities
image, text, file
License
proprietary
Released
2025-11-13

Pricing

Input
$1.25/Mtok
Output
$10.00/Mtok
Model ID
openai/gpt-5.1

Per-token prices show what the model costs upstream. On Switchy your team draws from one shared org credit pool - one plan, one balance for everyone.

Team cost calculator

Estimated monthly spend
$68.20
17.6M tokens / month
5 seats · 80 msgs/day

Switchy meters this against your org's shared credit pool - one plan, one balance for everyone.

Providers

ProviderContextInputOutputP50 latencyThroughput30d uptime
openai400k$1.25/Mtok$10.00/Mtok

Performance

Performance snapshots are collected daily. Check back after the next ingestion run.

Benchmarks

Public benchmark scores are not available yet for this model. Check back after the next ingestion run.

Works well with

Top MCPs

Compatibility data comes from first-party telemetry; once we have enough co-usage signal, top MCPs for this model will appear here.

How Switchy teams use it

Not enough Spaces have used this model yet to share anonymised team stats. We wait for at least 50 distinct Spaces per week before publishing any aggregate.

Starter prompts

Codebase Architecture Review

Review this codebase and identify the top 3 architectural patterns in use, then flag any files that violate those patterns or introduce technical debt. Provide file paths and specific line references.
Open in a Space →

Multi-Document Contract Analysis

Compare these five contracts and list any conflicting clauses, missing standard provisions, or unusual terms. For each issue, cite the specific document and section number.
Open in a Space →

Research Paper Synthesis

Synthesize these research papers into a 1000-word literature review. Identify consensus findings, contradictions, and gaps in the research. Cite paper titles inline.
Open in a Space →

Technical Documentation Consolidation

Consolidate these documentation files into a single getting-started guide. Preserve all code examples, remove redundancies, and ensure setup steps flow logically.
Open in a Space →

Long-Form Content with Deep Research

Write a 2000-word article on [topic] using these reference documents. Include specific data points and quotes, and ensure all claims trace back to the sources provided.
Open in a Space →

Example outputs

Illustrative - representative of the model's voice and quality, not literal recordings.

Prompt

Review this Python function for potential race conditions. It's meant to update a shared counter across multiple threads, but we're seeing inconsistent results in production.

Output

The function uses a simple read-modify-write pattern without synchronization primitives. Between reading `self.counter` and writing the incremented value back, another thread can interleave its own update, causing lost increments. You need either a threading.Lock around the entire operation, or switch to `threading.local()` if each thread should maintain its own counter. The 400K token context means I can also analyze your entire codebase if you share the threading architecture — that would reveal whether this pattern appears elsewhere and whether your test suite is missing concurrency coverage.

Notes

Demonstrates deep code reasoning with architectural awareness. The 400K context window enables whole-repository analysis, which is particularly valuable for systemic issues like threading bugs. Trade-off: at $10/Mtok output, verbose explanations of large codebases become expensive quickly.

Prompt

I'm attaching a 40-page technical specification PDF and three competitor product screenshots. Write a feature comparison table highlighting gaps in our current implementation, then draft API endpoint signatures to close those gaps.

Output

After analyzing the spec and screenshots, I've identified seven feature gaps. The most critical: competitor products support webhook retry policies with exponential backoff (your spec mentions this on page 23 but your screenshots show no UI for it), batch operations for resource updates (visible in Competitor B's screenshot but absent in your API docs), and granular permission scoping (Competitor A allows per-endpoint permissions; your current RBAC is role-level only). Here's the comparison table with priority rankings, followed by five new endpoint signatures using RESTful conventions that match your existing API style. Each includes request/response schemas and the specific spec section it addresses.

Notes

Showcases multimodal reasoning across documents and images within a single context. The file and image modalities let users upload specs and screenshots directly rather than copying text. Trade-off: processing 40 pages plus images consumes significant input tokens; at $1.25/Mtok that's negligible per query, but the model doesn't yet publish benchmark scores so reasoning quality relative to cost is unverified.

Prompt

Explain how quantum entanglement could affect distributed database consistency models. Assume I understand CAP theorem but not quantum mechanics. Use an analogy involving something from everyday logistics.

Output

Think of entangled particles like a pair of sealed envelopes that always contain opposite answers, determined only when opened — but the correlation is instant regardless of distance. In a distributed database, this could theoretically let geographically separated nodes 'agree' on state without message-passing, bypassing the CAP theorem's latency constraint. Imagine a logistics network where two warehouses instantly know each other's inventory levels without radio contact. Practically, though, quantum entanglement can't transmit classical information faster than light (no-communication theorem), so you still can't use it to coordinate database writes. What it *might* enable is cryptographically secure consistency verification: nodes could use shared entangled states to detect tampering or split-brain scenarios without trusting a central authority.

Notes

Highlights cross-domain synthesis and analogy generation tuned to the user's stated knowledge level. The model bridges abstract physics and concrete systems design without oversimplifying. Trade-off: the response is conceptually dense; users seeking quick factual answers rather than exploratory explanations may find the style too discursive.

Use-case deep-dives

Multi-document legal contract synthesis

When 400k context beats RAG for contract review workflows

A 12-person legal ops team needs to compare clauses across 80-page MSAs, SOWs, and amendment chains without losing thread. GPT-5.1's 400k context window means you drop the entire document set into one prompt and ask cross-reference questions in natural language—no vector database, no retrieval lag, no citation errors from chunking. At $1.25/Mtok input, a 300k-token contract bundle costs $0.38 to process, and the $10/Mtok output rate keeps multi-page summaries under $2. If your team reviews fewer than 50 complex deals per month and needs same-session follow-ups without re-uploading context, this is the call. Beyond that volume, you'll want a cheaper model with a RAG layer to avoid the output cost on repeated queries.

High-resolution design feedback automation

Using vision + long context for batch creative QA at agencies

A 6-person creative agency uploads 40 web mockups per client sprint and needs consistency checks on typography, color palette adherence, and accessibility contrast—across desktop and mobile variants. GPT-5.1's image modality plus 400k context lets you load all mockups in one prompt with the brand guide as reference text, then generate a structured QA report in a single pass. The output cost ($10/Mtok) means a 15k-token report runs $0.15, and you avoid the latency of sequential API calls. If you're running fewer than 100 design reviews per week and need same-context comparisons ("does screen 12 match the button style from screen 3?"), this beats chaining smaller models. Higher volume shops should batch reviews overnight with a cheaper vision model to control costs.

Real-time customer support escalation triage

When sub-second response time matters more than benchmark scores

A 20-seat SaaS support team fields 300 tickets daily and needs an AI layer to read the last 10 messages, pull account metadata from a CSV, and decide whether to route to billing, engineering, or self-service—all in under 2 seconds so the handoff feels instant. GPT-5.1's file modality means you can attach the account export directly without preprocessing, and the lack of public benchmarks is less relevant here than API latency and uptime SLA. At $1.25 input per Mtok, each triage call (roughly 8k tokens of context) costs about $0.01, and the 400k window future-proofs you if ticket threads grow. If your median ticket has fewer than 15 back-and-forth messages and you're optimizing for speed over the last 2% of accuracy, this is the right fit. Teams handling 1k+ tickets daily should benchmark against Anthropic's Claude for cost efficiency on repetitive routing logic.

Frequently asked

Is GPT-5.1 good for coding tasks?

Yes, GPT-5.1 handles coding well across most languages and frameworks. The 400k token context window means you can feed it entire codebases for refactoring or debugging. Without public benchmarks we can't compare it directly to Claude Sonnet 4 or Gemini 2.0 Flash Thinking, but early reports suggest strong performance on complex multi-file tasks.

Is GPT-5.1 cheaper than Claude Sonnet 4?

No. GPT-5.1 costs $1.25 input and $10 output per million tokens. Claude Sonnet 4 runs $3 input and $15 output, making it more expensive on paper, but GPT-5.1's output pricing is still high for long-form generation. For cost-sensitive workloads generating lots of text, consider Gemini 2.0 Flash at $0.10 input and $0.40 output instead.

Can GPT-5.1 handle 400k tokens in practice?

Yes, the full 400k context is usable, though quality can degrade past 300k tokens for complex reasoning tasks. It's reliable for ingesting large documents, legal contracts, or multi-file codebases. If you're hitting the limit regularly and need more, Gemini 2.0 Pro offers 2 million tokens at similar input pricing.

How does GPT-5.1 compare to GPT-4o?

GPT-5.1 is a step up in reasoning and context handling. The 400k window is 8x larger than GPT-4o's 128k, and anecdotal reports show better instruction-following on ambiguous prompts. Pricing is roughly 2x higher, so the upgrade makes sense for teams working with large documents or complex multi-turn conversations, less so for simple chat.

Should I use GPT-5.1 for customer support chatbots?

Probably not. The $10 per million output tokens adds up fast in high-volume chat scenarios. GPT-4o at $2.50 output or Gemini 2.0 Flash at $0.40 output will save you money without sacrificing quality for typical support queries. Use GPT-5.1 if your support requires deep document retrieval or complex multi-step reasoning.

Data last verified 7 hours ago.Sources aggregated hourly to weekly. See docs/architecture/model-directory.md.