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Reflection AI Tech Stack

Open-source AI model development and inference infrastructure

Software Development New York, NY 11–50 employees Privately Held

Reflection AI is building foundational AI infrastructure—training pipelines, post-training tooling, and inference systems—with a team of engineers and researchers from DeepMind, OpenAI, and Anthropic. The stack reveals heavy investment in distributed training (PyTorch, Megatron-LM, DeepSpeed, CUDA) and inference optimization (vLLM, SGLang, Triton), both actively being adopted, while the project list (red-teaming, automated QA, RL/SFT tooling, safety benchmarks) signals a focus on making frontier-grade model development accessible beyond closed labs.

Tech Stack 55 technologies

Core StackAshby Python TypeScript Docker Kubernetes PyTorch Rippling RAG Tableau Apache Spark React FastAPI Go gRPC LinkedIn Recruiter CUDA NCCL DeepSpeed JAX Megatron-LM SGLang vLLM Slurm CI/CD SQL Excel RLHF Ray Beam Triton+25 more
AdoptingvLLM SGLang

What Reflection AI Is Building

Challenges

  • Scaling technical organization
  • Reducing operational burden
  • Reducing friction in fine-tuning process
  • Establishing external partnerships
  • Ensuring high data quality
  • Hard-to-fill ai research roles
  • Reliability at scale
  • Cluster utilization and cost efficiency
  • Building new systems rather than maintaining legacy ones
  • Model factual accuracy

Active Projects

  • Reusable qa pipelines for post-training data
  • Post-training and inference ecosystem
  • Red-teaming evaluation pipeline
  • Automated qa methods for large data campaigns
  • Large-scale gpu infrastructure powering pre-training, post-training, and inference
  • Core software systems for research, training, and production environments
  • Apis, sdks, and internal platforms for rapid experimentation
  • Training infrastructure optimization
  • Automated safety benchmarks
  • Rl and sft tooling

Hiring Activity

Steady100 roles · 30 in 30d

Department

Engineering
35
HR
14
Data
12
Sales
10
Research
8
Legal
4
Product
3
Marketing
2

Seniority

Senior
66
Lead
13
Mid
8
Manager
5
Staff
1

Notable leadership hires: Product Policy Lead, Alignment Lead, Safety Lead, Open Source Lead, Brand Lead

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About Reflection AI

Reflection AI develops open-source infrastructure for training, fine-tuning, and serving large language models. The company operates as a lean, research-driven outfit (11–50 people, US and UK hiring) with deep expertise from prior roles at major AI labs. Their product surface spans distributed GPU orchestration (Slurm, Kubernetes), post-training pipelines (RLHF, automated QA, red-teaming evaluation), and inference APIs and SDKs—targeting researchers, practitioners, and organizations looking to run their own model development workflows. Active challenges include scaling the technical organization, optimizing cluster utilization, and ensuring data quality and model factual accuracy at scale.

HeadquartersNew York, NY
Company Size11–50 employees
Hiring MarketsUnited States, United Kingdom

Frequently Asked Questions

What is Reflection AI's tech stack?

Core stack: Python, TypeScript, PyTorch, Kubernetes, Docker. Training: Megatron-LM, DeepSpeed, CUDA, NCCL, JAX. Inference: vLLM, SGLang, Triton. Orchestration: Slurm, Ray, Beam. Recent adoption: vLLM and SGLang.

What is Reflection AI working on?

Post-training and inference ecosystems, red-teaming evaluation pipelines, automated QA for large data, safety benchmarks, RL/SFT tooling, GPU infrastructure optimization, and APIs/SDKs for rapid experimentation.

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