Anthropic acquires Stainless for $300M, pulling key developer tools from OpenAI and Google

Anthropic has acquired the dev tools startup used by OpenAI, Google, and Cloudflare | TechCrunch

Anthropic announced Monday it has acquired Stainless, a startup founded by former Stripe engineer Alex Rattray whose software is widely used by rival AI labs, including OpenAI and Google. Anthropic didn't disclose terms of the deal. However, The Information reported last week that Anthropic was in talks to acquire Stainless, which is backed by Sequoia Capital and Andreessen Horowitz, for more than $300 million. The acquisition will take a key infrastructure supplier out of the hands of Anthropic's competitors. The company told TechCrunch it will wind down all hosted Stainless products, including its SDK generator. An Anthropic spokesperson said Stainless customers will still own the SDKs they've generated to date, and have full rights to modify and extend them however they wish. The New York-based startup, founded in 2022, rose to prominence in the emerging AI industry for automating the creation and maintenance of software development kits, or SDKs -- the libraries developers use to interact with APIs. Rattray developed software that could take API specifications and turn them into production-ready SDKs across multiple programming languages, including Python, TypeScript, Kotlin, Go, and Java. It became a popular tool because the platform automatically updates the SDKs as APIs change and eliminated the time-consuming process of manually maintaining them. The technology is particularly valuable to companies like Anthropic, OpenAI, Google, Replicate, Runway, and Cloudflare that are building AI agents that can connect to external software and complete tasks on behalf of users. Stainless's SDK tools are an easy way to build and maintain those connections -- but going forward, the tools will only be available to Anthropic, not its competitors. According to Anthropic, Stainless software has powered the generation of every official Anthropic SDK since the earliest days of its API. "I started Stainless because SDKs deserve as much care as the APIs they wrap," Rattray said in a press release posted Monday. "Anthropic was one of the first teams to bet on this with us. We have been watching what developers have built on Claude over the last few years, which made bringing our teams together an easy decision. The team gets to keep doing the work we love, on the platform where it matters most."

Anthropic's Stainless steal tightens grip on AI dev tooling

Claude maker nabs SDK and MCP tooling biz, plans to sunset platform Anthropic is acquiring Stainless, a maker of software development tools that counts rivals OpenAI and Google as clients. The deal, reportedly for more than $300 million, demonstrates Anthropic's continued interest in exercising greater control over the AI technical stack and suggests that speculation about the commodification of models is on the mark. Frontier models will not be so strong that they serve as a moat or barrier to competition, but the tooling and workflow around those models should provide some cover. Anthropic has made several recent acquisitions that give it more say in the software that orchestrates model input, output, and tool calls. In December, it snarfed Bun, a JavaScript runtime, package manager, and test runner. Two months later, it bought Vercept, a company focused on AI-mediated computer usage. In April, it admitted healthcare AI startup Coefficient Bio into the fold. Enter Stainless. "Hundreds of companies rely on Stainless to generate SDKs, CLIs, and MCP servers - the libraries, command-line tools, and connectors that let developers and agents use an API," Anthropic said in its announcement. "Stainless turns an API spec into SDKs across TypeScript, Python, Go, Java, Kotlin, and more." SDKs are sticky. Whoever ships the cleanest one wins the long tail of developer mindshare One of those hundreds of companies is OpenAI - its Python, Node, Java, Go, and Ruby clients are based on SDKs generated by Stainless. With Stainless now planning to shutter its platform on September 1, 2026, OpenAI and other industry customers will have to shoulder the burden of maintaining existing SDKs and find equivalent tools elsewhere. It should be noted that OpenAI in March agreed to acquire Python tool maker Astral, one of six such deals this year. So far, the Astral acquisition hasn't affected the ability of Anthropic or developers to use Astral's tooling. Jan Schmitz, who runs AI analytics biz BrightBean, described the Stainless acquisition as both offensive and defensive. "By acquiring the SDK infrastructure used across the industry, Anthropic gets visibility into how competitors evolve their APIs, even if only through generator usage patterns, and it gains the ability to set the pace on integration tooling," he said in a blog post. "The defensive read: If OpenAI or Google had bought Stainless first, the damage to Anthropic's developer ecosystem would have been worse. SDKs are sticky. Whoever ships the cleanest one wins the long tail of developer mindshare." Schmitz also argues that Anthropic sees value in controlling the MCP standard that it proposed and promoted. "The pattern looks like this: Control the standard by giving it away, then control the implementation by owning the toolchain," he said, noting that Google followed that playbook with Kubernetes and then making GKE the leading managed version. ®

Anthropic acquires Stainless to strengthen Claude's developer tooling

Founded in 2022 by former Stripe engineer Alex Rattray, Stainless converts API specifications into production-ready SDKs across languages, including Python, TypeScript, Kotlin, Go, and Java. Stainless does not sell primarily to enterprises, but its tools form part of the software development chain that enterprise teams may rely on. They help generate SDKs, documentation, and MCP servers that developers can use to connect AI models, cloud services, and APIs to business applications. In a statement, Stainless said it will wind down all hosted products, including its SDK generator, as the team shifts focus to Claude Platform capabilities and connecting agents to APIs. Existing customers will retain the right to modify and extend SDKs they have already generated. This could have competitive implications. Stainless has listed OpenAI, Google DeepMind, Perplexity, Groq, and Cloudflare among its customers, showing how widely its tools have been used across the AI and cloud infrastructure markets. Some customers may need replacement tooling or in-house alternatives to update and maintain those SDKs as their APIs evolve. The acquisition gives Anthropic more control over a growing layer of developer infrastructure as AI vendors compete to make their models easier to integrate into enterprise software environments. That could strengthen Claude's appeal to teams building agentic systems, while prompting existing Stainless customers to reassess how they generate and maintain SDKs over time.

Anthropic in talks to buy AI tools startup Stainless for over $300 million: The Information

AI firm Anthropic is reportedly in advanced talks to buy Stainless for over $300 million. Stainless builds software for easier AI model access. This comes as Anthropic also explores raising at least $30 billion in new funding. The company's valuation could exceed $900 billion. Anthropic is in advanced talks to acquire Stainless for more than $300 million, according to a report by The Information on Wednesday. The deal has not yet been finalised, and the terms could still change. Part of the payment may also be made using Anthropic shares, the report added. Founded in early 2022 by Alex Rattray, Stainless builds software that helps developers access and use artificial intelligence models more easily. Its customers include Anthropic, OpenAI and Google. If the deal goes through, Anthropic would take ownership of a major tool that developers use to access AI models from companies such as OpenAI and Google. Demand for Stainless' tools has reportedly grown alongside the rise of AI agents such as Claude Code and OpenCode. OpenAI had previously developed its own software development kit, but later adopted Stainless' tools because maintaining the system internally became difficult and resource-heavy. Stainless has also built software linked to Model Context Protocol (MCP), a framework launched by Anthropic in November 2024. This comes as Bloomberg reported on Wednesday that Anthropic is in early discussions with investors to raise at least $30 billion in fresh funding. The report said the round could value the company at more than $900 billion, excluding the investment itself. That would be more than double Anthropic's reported $380 billion valuation from its February funding round. Bloomberg added that discussions are ongoing, and no formal agreement or term sheet has yet been signed. Founded in 2021 by former OpenAI employees, Anthropic has emerged as one of the leading companies in the AI industry. It has developed a range of AI products focused on tasks such as coding and cybersecurity.

Anthropic Buys Stainless, Acquiring Startup Behind OpenAI's Developer Libraries

Anthropic has acquired Stainless in an effort to "improve developer experience and the connections between agents and external systems." Stainless was founded in 2022 by Alex Rattray. The New York-based developer tools company that helps organizations build and maintain world-class software development kits (SDKs) and developer interfaces for their APIs, according to their LinkedIn. "I started Stainless because SDKs deserve as much care as the APIs they wrap. Anthropic was one of the first teams to bet on this with us. We have been watching what developers have built on Claude over the last few years, which made bringing our teams together an easy decision. The team gets to keep doing the work we love, on the platform where it matters most," Rattay said. Stainless will be winding down its products, including its SDK generator and halting all new products, the firm said in a press release. The company's clients previously included Google DeepMind, Meta and Anthropic's rival, OpenAI. OpenAI originally built an internal software development kit, but later moved to Stainless' tooling after maintaining the system in-house became increasingly complex and resource-intensive. Stainless has also developed software tied to Anthropic's Model Context Protocol (MCP), a framework introduced in November 2024. The transaction is worth approximately $300 million, The Information previously reported prior to the competition of the deal. This acquisition comes as Anthropic is reportedly holding discussions with investors regarding a new funding round that would place the company's valuation at $800 billion, more than doubling its $350 billion mark in February. The artificial intelligence company also recently launched Claude Mythos Preview, a model that can identify software vulnerabilities, to a small number of companies for testing. The launch is reportedly so powerful that the company restricted access due to cybersecurity concerns, and this has only strengthened its positioning ahead of a potential IPO later this year. Photo: Shutterstock Market News and Data brought to you by Benzinga APIs To add Benzinga News as your preferred source on Google, click here.

Anthropic Acquires Dev Tools Startup Stainless used by OpenAI, Google

Reports suggest Anthropic may've paid out $300 million but that's a small price one pays to remove a key infrastructure off the competitors' cupboards In political terms we'd describe it as a coup d'état. In business terms one might not go that far and describe it as a smart move in a race for AI hegemony. Whatever be the case Anthropic seems to have taken a key supplier out of the hands of its competitors by acquiring Stainless - a startup whose software has been used by rival labs such as OpenAI and Google. The New York-based startup founded by former Stripe engineer Alex Rattray whose software was used widely by OpenAI and Google, has said it plans to wind down all hosted Stainless products, including their popular SDK generator. The frontier of AI is shifting from models that answer to agents that act -- and agents are only as capable as the systems they can reach. Today, Anthropic is acquiring Stainless, a leader in SDKs and MCP server tooling, to extend that reach even further, the company said in a post. However, the statement did not contain any details about the terms of the deal though some media reports last week claimed that the acquisition of Stainless, backed by the likes of Sequoia Capital and Andreessen Horowitz, could have netted over $300 million for the founders and the early investors. From Anthropic's perspective, what's $300 million if the deal effectively removes a major infrastructure supplier out of the hands of one's competitors. "Stainless is joining Anthropic to accelerate our mission to improve developer experience and the connections between agents and external systems," Rattray wrote in a blog post. He further noted that as his team now focuses on Claude Platform capabilities and connecting agents to APIs, Stainless will be winding down all hosted Stainless products, including our SDK generator. Starting today, new signups, projects, and SDKs will not be available, he said. However, Anthropic noted that the acquiree company will continue to own the SDKs they've generated to date and have full rights to modify and extend them as they wish. Stainless rose to prominence in recent years as the AI industry sought ways to automate creation and maintenance of software development kits or SDKs, which are nothing but libraries that developers use to interact with APIs. Rattray and his team developed software that took API specifications and turned them into production-ready SDKs across multiple programming languages like Java, Go, Python and more. The tool gained popularity as the platform could automatically update the SDKs with changes in the API, which removed the rather gruelling process of manual maintenance. Companies in the AI domain as well as those building AI agents find this useful as they can connect to external software and complete tasks on behalf of users. The SDK tools from Stainless is easy to build and maintain the connections. However, from now on only Anthropic would be able to use them. "Stainless has shaped how developers experience the Claude API since the start, and it's been great to work with them on that," says Katelyn Lesse, Head of Platform Engineering at Anthropic. "Agents are only as useful as what they can connect to. We're excited to bring the Stainless team into Anthropic to advance Claude's ability to connect to data and tools." Rattray responded with equal candour. "Great APIs are more essential now than ever. Nobody understands this better than Anthropic," he said while pointing out that Anthropic was one of their oldest and closest partners where Stainless had the opportunity to work closely on almost every Claude API launch. "We've also admired their industry leadership in connecting agents to complex APIs, and their incredible reach with developers and enterprises alike," Rattray said in his blog noting that this was the reason Stainless was joining Anthropic. Looks like a marriage made in heaven.

Anthropic in talks to buy dev tools startup for $300 mln- The Information By Investing.com

Investing.com-- Anthropic is in advanced talks to buy developer tools startup Stainless for at least $300 million, The Information reported on Tuesday, citing a person with knowledge of the deal. The startup sells software to artificial intelligence model makers including Anthropic, OpenAI, and Google, that helps developers more quickly access AI models. Get more breaking news on the biggest AI firms by subscribing to InvestingPro Stainless' software can also be used by AI agents, and has seen growing demand in recent months with the increasing popularity of agents such as OpenClaw. Anthropic's potential acquisition of Stainless also comes amid a greater focus by the startup on AI for enterprise and business applications- a move that is viewed as highly lucrative for the company. The company is targeting a $900 billion valuation in a massive new funding round, Bloomberg reported earlier on Tuesday, more than twice its $380 billion valuation during a funding round in February.