SWE-2

SWE-2

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 is Cognition’s advanced coding model designed to improve software engineering performance while reducing the cost of agentic coding workflows. The model is post-trained from Kimi K3 and uses reinforcement learning to optimize multiple reasoning-effort levels within a single training run. SWE-2 is designed to explore codebases more selectively, begin implementation sooner, and complete tasks with fewer redundant reads and reasoning steps than earlier Cognition models. Its capabilities include code generation, debugging, test creation, verification, repository analysis, and complex terminal-based software engineering tasks. The model also emphasizes stronger engineering judgment, end-to-end test coverage, instruction following, and evidence-based verification of user assumptions. SWE-2 is available through Devin Desktop and Devin CLI, with broader rollout planned across Devin Web and Fusion.

Platforms Supported

Windows
Mac
Linux
Cloud
On-Premises
iPhone
iPad
Android
Chromebook

Platforms Supported

Windows
Mac
Linux
Cloud
On-Premises
iPhone
iPad
Android
Chromebook

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, engineering teams, AI coding agent users, DevOps professionals, and organizations that need capable agentic software engineering with lower execution cost and more efficient reasoning

Support

Phone Support
24/7 Live Support
Online

Support

Phone Support
24/7 Live Support
Online

API

Offers API

API

Offers API

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
Free Trial

Pricing

$20/month
Free Version
Free Trial

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

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

  • The biggest thing that stands out is the cost-performance balance. SWE-2 is not just trying to top one benchmark; it is trying to get very close to frontier coding performance at a much lower cost. For developers, that matters a lot. Coding agents can burn through tokens quickly when they are reading files, making edits, running tests, and iterating. A model that performs near the top while being meaningfully cheaper is much easier to use every day. I also like that SWE-2 seems built for real software engineering workflows, not just isolated code snippets. The strong DeepSWE and Terminal-Bench results make it especially interesting for repo-level tasks, debugging, tool use, and longer agent runs.

Cons

  • Benchmarks are useful, but real projects bring messy architecture, flaky tests, undocumented behavior, and weird edge cases.

Training

Documentation
Webinars
Live Online
In Person

Training

Documentation
Webinars
Live Online
In Person

Company Information

Anthropic
Founded: 2021
United States
claude.ai

Company Information

Cognition
Founded: 2023
United States
cognition.com

Alternatives

Alternatives

GPT-5.6 Sol

GPT-5.6 Sol

OpenAI
GPT-6 Astra

GPT-6 Astra

OpenAI
GPT-5.6 Sol

GPT-5.6 Sol

OpenAI
Claude Fable 5

Claude Fable 5

Anthropic
SWE-1.7

SWE-1.7

Cognition
Claude Opus 5

Claude Opus 5

Anthropic
SWE-1.6

SWE-1.6

Cognition

Categories

Categories

Integrations

.NET
C
C#
C++
CSS
Devin Desktop
Go
HTML
JavaScript
Kotlin
Objective-C
PowerShell
Python
Ruby
Rust
Scala
Solidity
Swift
XML
YAML

Integrations

.NET
C
C#
C++
CSS
Devin Desktop
Go
HTML
JavaScript
Kotlin
Objective-C
PowerShell
Python
Ruby
Rust
Scala
Solidity
Swift
XML
YAML
Claim Claude Fable 5.1 and update features and information
Claim Claude Fable 5.1 and update features and information
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