Claude 3.5/4 Series
Anthropic continues updating Claude series, leading in coding and reasoning capabilities.
Overview
In 2025, Anthropic continued iterating the Claude series. Claude 3.5 Sonnet performed excellently on coding tasks, becoming many developers' preferred AI assistant. Claude 3.5 Sonnet supported computer use capabilities, able to directly operate computer interfaces to complete tasks. Subsequent versions continued improving in reasoning, long-context handling, and multimodal understanding, fiercely competing with the GPT series. Anthropic's product strategy focused on safety and reliability, gaining wide adoption in enterprise applications.
Study Notes
Background, mechanics, impact, and key takeaways in one read
Background & Context
In 2025 Anthropic's Claude line entered a dense iteration cycle and became one of the strongest variables in coding and reasoning. Claude 3.5 Sonnet launched in June 2024, beating the company's own flagship Opus on several benchmarks at about 60% of the price and higher speed, and its October update brought the public beta of computer use, letting the model view screens, move the mouse, click, and type as one of the first general agents to truly operate graphical interfaces. Claude 3.7 Sonnet, released on February 24, 2025, adopted hybrid reasoning: the same model switches between instant answers and extended thinking, and it led decisively on the SWE-bench Verified coding benchmark. Anthropic's strategy was clear: coding capability as the spear and the safety narrative as the shield, steadily winning enterprise market share.
Key Points
- 1Claude 3.5 Sonnet (June 2024) beat the flagship Opus at lower price, resetting the value benchmark.
- 2The October 2024 update brought computer use in public beta: the model operates graphical interfaces directly.
- 3Claude 3.7 Sonnet (February 24, 2025) introduced hybrid reasoning, switching between instant and extended thinking.
- 4It led decisively on coding benchmarks like SWE-bench Verified, becoming a developer favorite.
- 5Interaction innovations like Artifacts pushed Claude from chat tool to collaborative workbench.
How It Works
Two technical themes define this Claude generation. First, hybrid reasoning: the model allocates a thinking budget in its system prompt, answering simple queries directly while emitting a structured extended-thinking block before answering complex ones, a deliberate contrast with OpenAI's o series that hides reasoning from users, since Anthropic chose to make reasoning explicit and inspectable. Its lead on SWE-bench Verified shows extended thinking pays off strongly on real software-engineering tasks like locating bugs and editing across files. Second, computer use: the model perceives screen state from screenshots rather than structured APIs and outputs mouse coordinates and keystrokes, closing the loop with the environment. This route bypasses the integration problem of writing an API per application, at the cost of a coarse action space, slow speed, and error accumulation, foreshadowing both the opportunity and the trap of later GUI agents.
Impact & Legacy
Claude 3.5 and 3.7 put Anthropic on the throne of coding AI: the SWE-bench lead converted directly into commercial results, with enterprise and developer subscriptions surging and tools like Claude Code and MCP extending influence from the model layer to the toolchain, driving Anthropic's annualized revenue into the billions by 2025. Hybrid reasoning also changed the industry's product definition of a reasoning model: visible thinking with controllable budgets became a design pattern widely borrowed, including Google's thinking modes. Computer use opened the GUI-agent category; while not yet production-ready itself, it provided proof of concept for agent products after 2025. Limits exist as well: 3.7's thinking mode adds latency and token cost, and the coding crown changed hands repeatedly in 2025 under fierce attacks from OpenAI, Google, and open models.
Key Takeaways
- Coding benchmarks like SWE-bench have become the hardest product metric and marketing battlefield.
- Hybrid reasoning makes the thinking budget a user-controlled product parameter, not a hidden internal mechanism.
- Computer use bypasses API integration via screenshots plus mouse-keyboard actions, but with a coarse action space.
- Model competition has spilled from scores into toolchains and protocols like MCP and Claude Code.
Glossary
A product design where one model switches between instant answers and extended thinking, with reasoning visible to the user.
A benchmark evaluating software-engineering ability on real GitHub issues and patches, with the Verified subset human-filtered.
An agent capability where the model perceives screens via screenshots and outputs mouse and keyboard actions.