Scale AI, Inc. is an American artificial intelligence infrastructure and software company headquartered in San Francisco, California. Originally focused on data annotation, the company expanded to offer reinforcement learning from human feedback (RLHF) services, large language model (LLM) evaluation, and enterprise software suites for building and deploying AI applications. Its customers span commercial sectors and world governments, including the United States military and the Qatari government.
The company’s research arm, the Safety, Evaluation and Alignment Lab, focuses on evaluating and aligning LLMs and co-created the benchmark Humanity's Last Exam. Scale AI outsources data labeling through its subsidiaries, Remotasks, which focuses on computer vision and autonomous vehicles, and Outlier, which focuses on annotating data for LLMs. In June 2025, Meta Platforms acquired a 49% non-voting stake in Scale AI for over $14 billion, with CEO Alexandr Wang departing to join Meta.
History
Early years (2016–2019)
Scale was founded in 2016 by Alexandr Wang and Lucy Guo through Y Combinator. The pair had previously worked together at Quora. Initial investors included Dragoneer Investment Group, Tiger Global Management, and Index Ventures. Guo was fired in 2018. In August 2019, after Peter Thiel’s Founders Fund made a $100 million investment, Scale's valuation exceeded $1 billion, achieving unicorn status.
Growth (2019–2025)
Scale contracted with the United States Department of Defense in 2020. In May 2021, Michael Kratsios, former U.S. Chief Technology Officer under the Trump administration, joined as managing director and head of strategy. By July 2021, Scale reached a valuation of $7 billion after a financing led by Greenoaks, Dragoneer, and Tiger Global, driven by increased demand for data labeling.
In January 2022, Scale won a $250 million contract to give American federal agencies access to its tools. In February 2022, it developed the Automated Damage Identification Service in response to the Russian invasion of Ukraine, analyzing satellite imagery to measure building damage and geotagging reports for humanitarian groups. In November 2022, Time recognized Scale on its Best Inventions of 2022 list, and the company opened an office in St. Louis.
In January 2023, Scale laid off 20% of its workforce. In May 2023, it signed a deal with the US Army’s XVIII Airborne Corps, becoming the first AI company to deploy its LLM (Donovan) on a classified network. In August 2023, Scale became OpenAI’s "preferred partner" to fine-tune GPT-3.5, and its services were used to create ChatGPT. That same month, Scale’s evaluation platform was used at DEF CON for the first generative AI red team event, testing models from various companies. In December 2023, Scale contributed to Meta’s Purple Llama initiative, a security framework for open generative AI models.
In February 2024, the Department of Defense selected Scale to test and evaluate its LLMs for military purposes under a one-year contract. In March 2024, Scale reached a valuation of nearly $13 billion after Accel led a funding round. In May 2024, Scale raised an additional $1 billion with new investors including Amazon and Meta Platforms, bringing its valuation to $14 billion. In August 2024, Scale signed an agreement with the US AI Safety Institute to collaborate on research, testing, and evaluation of AI models.
In December 2024, a former employee sued Scale alleging wage theft and worker misclassification; a second employee filed a similar suit the following month. In January 2025, several contractors sued Scale alleging psychological harm from exposure to disturbing content. That month, The Conversation reported that Scale and Meta had previously teamed up to create and sell Defense Llama, an LLM product for military purposes. Scale also took out a full-page ad in The Washington Post appealing to President Donald Trump to "win the AI war". Later in January, Scale and the Center for AI Safety released Humanity's Last Exam, a benchmark for AI systems. Scale also assisted in developing benchmarks EnigmaEval, MultiChallenge, and MASK.
In February 2025, Scale agreed to a five-year partnership with the Qatari government to improve government services via AI tools and training, signed at the Web Qatar 2025 Summit. Also in February, Scale became a third-party evaluator of AI models for the US AI Safety Institute. In March 2025, Scale reached a multimillion-dollar deal with the Department of Defense for the Thunderforge project, a "major step in U.S. military automation" to use AI in planning and executing military movements, awarded by the Defense Innovation Unit with Anduril Industries and Microsoft, initially for USINDOPACOM and EUCOM. In April 2025, Scale released Scale Evaluation, a platform for testing LLMs against benchmarks to identify weaknesses and flag training data needs.
Additional investment from Meta (2025)
On June 10, 2025, Meta Platforms agreed to purchase a 49% non-voting stake in Scale AI for $14.8 billion. Scale remained a standalone, independent entity. Former CEO Alexandr Wang took a top position inside Meta and was replaced by Jason Droege, Scale's chief strategy officer and former Uber executive.
Scale Labs
In March 2026, the company launched Scale Lab, an initiative to advance AI research and development.
Operations and Services
Scale AI provides a data engine that includes data annotation, RLHF, and model evaluation. Its platform supports computer vision, autonomous vehicles, and LLMs. The company operates an LLM Red Team that conducts human adversarial testing to identify vulnerabilities, biases, and safety risks. This team has worked with OpenAI, Google DeepMind, and national AI Safety Institutes to evaluate systems against threats like cybersecurity vulnerabilities, jailbreaks, and agentic AI behaviors.
Government and Military Contracts
Scale's government work includes contracts with the US Department of Defense, the US Army, and the Defense Innovation Unit. Projects include Donovan, an LLM deployed on classified networks, and Thunderforge, an AI-based military decision-making tool. Internationally, Scale partnered with Qatar to improve social program efficiency.
Commercial Partnerships
Commercial customers have included Google, Microsoft, Meta, General Motors, OpenAI, and Time. Scale's partnership with OpenAI involved fine-tuning GPT-3.5, contributing to ChatGPT's development. The company also contributed to Meta's Purple Llama initiative.
Controversies and Legal Issues
Scale faced lawsuits in late 2024 and early 2025 alleging wage theft, worker misclassification, and psychological harm to contractors. These cases highlight ongoing concerns about labor practices in the AI data labeling industry.