SWE-2 Flash

SWE-2 Flash

Cognition
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About

Claude Fable 5.1 is Anthropic’s advanced AI model for coding, knowledge work, research, and long-running agentic tasks. It is designed to improve on Claude Fable 5 with stronger performance across software engineering, scientific research, multidisciplinary reasoning, computer use, business workflows, and complex problem solving. The model can handle extended multi-step work, verify its own results, diagnose difficult software issues, and operate effectively across tool-heavy workflows. Anthropic also reduced cache-read pricing for Fable 5.1, lowering typical usage costs compared with Fable 5 and creating larger savings for highly agentic workloads. Fable 5.1 includes updated safeguards intended to reduce false positives while allowing more legitimate cybersecurity tasks such as vulnerability discovery for defensive purposes. The model is available through Claude products, the Claude API, Amazon Web Services, Google Cloud, and Microsoft Azure.

About

SWE-2 Flash is an AI coding model developed by Cognition to provide fast, cost-efficient software engineering capabilities for autonomous development agents. Built on Thinking Machines' Inkling-Small foundation model, it uses mid-training and reinforcement learning to improve coding performance, reasoning, and task execution. The model supports software development activities such as code generation, code reviews, feature development, documentation updates, and automated engineering workflows. SWE-2 Flash generates approximately 200 tokens per second, making it three times faster and five times less expensive than the larger SWE-2 model. Its 276-billion-parameter mixture-of-experts architecture activates approximately 12 billion parameters during inference to balance performance and computational efficiency. SWE-2 Flash is available through Devin Desktop and CLI, with Cognition also developing a secure model-weight sharing program for trusted research and enterprise partners.

Platforms Supported

Windows Not Supported
Mac Not Supported
Linux Not Supported
Cloud Supported
On-Premises Not Supported
iPhone Not Supported
iPad Not Supported
Android Not Supported
Chromebook Not Supported

Platforms Supported

Windows Not Supported
Mac Not Supported
Linux Not Supported
Cloud Supported
On-Premises Not Supported
iPhone Not Supported
iPad Not Supported
Android Not Supported
Chromebook Not Supported

Audience

Software developers, researchers, enterprises, analysts, knowledge workers, and AI application teams that need advanced coding, reasoning, research, and long-running agentic capabilities

Audience

Software developers, AI coding assistant users, software engineering teams, DevOps professionals, autonomous agent developers, AI researchers, enterprise development organizations, and cybersecurity researchers seeking fast, cost-efficient AI coding, automated code reviews, feature implementation, software maintenance, technical reasoning, and agentic development workflows

Support

Phone Support Not Supported
24/7 Live Support Not Supported
Online Supported

Support

Phone Support Not Supported
24/7 Live Support Not Supported
Online Supported

API

Offers API Supported

API

Offers API Not Supported

Screenshots and Videos

Screenshots and Videos

Pricing

$10 per 1M tokens (input)
$10 per million input tokens and $50 per million output tokens
Free Version Not Supported
Free Trial Not Supported

Pricing

$20/month
Free Version Supported
Free Trial Not Supported

Reviews/Ratings

Overall 5.0 / 5
ease 5.0 / 5
features 5.0 / 5

Reviews/Ratings

Overall 5.0 / 5
ease 5.0 / 5
features 5.0 / 5
design 5.0 / 5
support 5.0 / 5

Pros & Cons from Real Users

Pros

  • This feels like the model you reach for when the work is genuinely difficult. Not every task needs Fable, but for complex coding, long-horizon agents, deep research, and big messy knowledge-work projects, Fable 5.1 looks built for the hard stuff. The 1M-token context window is a huge advantage. For developers and AI power users, that means you can work across large repos, long docs, research sets, transcripts, spreadsheets, and project history without constantly chopping everything into pieces. I also like that Anthropic specifically calls out document, spreadsheet, and slide work. That makes it feel useful beyond coding alone — more like a high-end model for serious professional workflows.

Cons

  • The downside is price and complexity. Anthropic says most workloads should start with Claude Opus 5, and Fable 5.1 is better reserved for demanding reasoning or cases where Opus 5 still falls short.

Pros & Cons from Real Users

Pros

  • This is the kind of model I would use all day for normal engineering work. It is fast enough that it does not feel like I am waiting on the model, but it is still strong enough for feature work, code review, docs, automations, and debugging. The speed is probably the biggest win. Cognition says it runs at around 200 tokens per second versus about 60 for SWE-2, and that difference matters a lot once an agent starts iterating through files and tools. The cost-performance balance is also really good. It is one-fifth the price of SWE-2, while scoring 45.5 on FrontierCode 1.1 Main, 60.1 on DeepSWE 1.1, and 89.9 on SWE-Bench Pro v2 Hard.

Cons

  • My main complaint is that it is not the model I would choose for the hardest repo-wide work. SWE-2 still has a noticeable edge on some tougher benchmarks, so I would move up when the task really needs it.

Training

Documentation Supported
Webinars Not Supported
Live Online Not Supported
In Person Not Supported

Training

Documentation Supported
Webinars Not Supported
Live Online Not Supported
In Person Not Supported

Company Information

Anthropic
Founded: 2021
United States
claude.ai

Company Information

Cognition
Founded: 2023
United States
cognition.com

Alternatives

Alternatives

GPT-6.1 Sol

GPT-6.1 Sol

OpenAI
GPT-6.1 Sol

GPT-6.1 Sol

OpenAI
Inkling

Inkling

Thinking Machines Lab

Categories

AI Coding Models Supported
AI Models Supported
AI Vision Models Supported
Foundation Models Supported
Multimodal Models Supported

Categories

AI Coding Models Supported
AI Models Supported

Integrations

.NET Supported
C Supported
C++ Supported
CSS Supported
Devin Supported
Devin Desktop Supported
HTML Supported
JavaScript Supported
Kubernetes Supported
Objective-C Supported
PHP Supported
PowerShell Supported
Python Supported
R Supported
Rust Supported
SQL Supported
Solidity Supported
Swift Supported
TypeScript Supported
XML Supported

Integrations

.NET Supported
C Supported
C++ Supported
CSS Supported
Devin Supported
Devin Desktop Supported
HTML Supported
JavaScript Supported
Kubernetes Supported
Objective-C Supported
PHP Supported
PowerShell Supported
Python Supported
R Supported
Rust Supported
SQL Supported
Solidity Supported
Swift Supported
TypeScript Supported
XML Supported
Claim Claude Fable 5.1 and update features and information
Claim Claude Fable 5.1 and update features and information
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