Developer Tools startups in San Francisco

Cognition

San Francisco

The company is an applied AI lab that builds end-to-end software agents and collaborative AI teammates, enabling engineers to focus on more interesting problems and empowering teams to pursue ambitious goals; it markets Devin as the first A

LMArena

San Francisco

LMArena, created by UC Berkeley researchers, is an open platform for accessing and comparing leading AI models, where users rate responses and help build a public, real-world leaderboard to increase transparency in AI progress.

Cartesia

San Francisco

Cartesia builds the next generation of AI—ubiquitous, interactive intelligence that runs wherever you are. It maintains a Discord community (discord.com/invite/cartesia) and showcases its work at cartesia.ai.

E2B

San Francisco

E2B is a Series A startup building the next hyperscaler for AI agents. It has seven figure revenue and has raised over $32M from investors including Insight Partners, serving Perplexity, Hugging Face, Manus, and Groq in San Francisco and Pr

Wordware

San Francisco

Wordware offers a web-hosted IDE that lets non-technical domain experts collaborate with AI engineers to build task-specific AI agents, treating prompting as a programming language for natural language programming and agent orchestration.

Judgment Labs

San Francisco

Judgment Labs provides infrastructure for Agent Behavior Monitoring (ABM) to observe post-deployment autonomous-agent behavior at scale, serving hundreds of teams. It has raised over $30 million from notable investors and positioned as a le

Indent

San Francisco

Indent is a platform for large engineering teams, used for incident response, code review, and data analysis with minimal setup. It provides a cloud AI software engineer that handles the entire job, including real-world tasks like analyzing

Mem0

San Francisco

Mem0 provides a universal, self-improving memory layer for LLM applications, enabling personalised AI experiences while reducing costs and boosting user delight. It markets itself as "The memory layer for Personalized AI."

Momentic

San Francisco

**The AI-native automated testing platform** Momentic is the modern alternative to Selenium, Cypress, and Playwright. We help software companies ship faster with reliable end-to-end tests that write themselves. World-class engineering team

ZeroPath

San Francisco

ZeroPath, founded by security researchers formerly from Tesla and Google, helps developers ship secure code faster with a developer-friendly solution that changes how teams approach application security.

Dedalus Labs

San Francisco

Dedalus Labs provides an MCP gateway and servers, unifying the AI agents ecosystem with a drop-in API. It enables users to go from idea to production in a single click, mixing models from any vendor with MCP marketplace tools.

Dosu

San Francisco

Dosu makes engineering knowledge accessible to developers, empowering the community with AI-driven tools. A small San Francisco-based team backed by over $9M in funding, its software is used on thousands of open-source GitHub repos and supp

Statics

San Francisco

Statics is building Context OS for AI agents to optimize context and improve LLM performance. Backed by Tier 1 VCs, including a16z, it works with a portion of Forbes AI 50 and is an early-stage company led by Johnny Wang.

Assert

San Francisco

Assert.dev is building a modern code-review interface for AI-enabled development, guided by the slogan "Code is meant to be run, not read." It operates the assert.dev website and aims to modernize code review for the AI era.

Magic Patterns

San Francisco

Magic Patterns is a fast-moving startup with an office in San Francisco and additional offices across North America, known for its small yet mighty team and rapid growth as it aims to transform the future of software building.

Artifact

San Francisco

Artifact is a collaborative IDE for hardware engineers that accelerates the entire lifecycle, from design to sustainment, by building a verifiable AI copilot with an intuitive UI that mirrors how hardware is actually built. It has raised $3

Mesa

San Francisco

Mesa builds next-generation developer tools focused on code review, quality, and productivity. Backed by Innovation Endeavors, Essence VC, South Park Commons, and leaders like Thomas Wolf of Hugging Face, it aims to reshape software develop

Reflex

San Francisco

Reflex is an open-source framework and hosted platform that helps Python developers build, deploy, and manage web apps, backed by an ecosystem of tools and services to speed development while preserving flexibility; founded by open-source m

Continue

San Francisco

Continue is a San Francisco–based startup (YC S23) backed by Heavybit and notable angels; Siemens is rolling out Continue, which has 26k+ GitHub stars and 2M+ downloads, and focuses on amplifying developers at the intersection of AI and dev

CloudCruise

San Francisco

CloudCruise offers a platform to design once and ship fast, reliable browser agents, triggerable via API, with automatic issue repair to keep agents running smoothly.

Weave

San Francisco

Weave applies machine learning to engineering data, scanning every pull request to estimate its duration and evaluate review quality and work type, enabling teams to gain visibility and improve predictability in software delivery.

PostHog

San Francisco

PostHog offers a product analytics platform to help create successful products. It gained traction, including B2B Hacker News launch, 100k+ users, 97% word-of-mouth growth, and top 0.01% GitHub ranking, hosted in US or EU with SOC2, GDPR, a

Merge API

San Francisco

Merge is a leading provider of customer-facing integrations and agent tools for frontier LLMs, serving thousands of customers including Fortune 500s and B2B SaaS firms, with offices in San Francisco, New York, and Berlin.

Supergood

San Francisco

Supergood combines observability data with human-in-the-loop code generation to create new integrations and fix existing ones.

Recall.ai

San Francisco

Recall.ai provides infrastructure for processing meeting data and metadata, enabling enterprises to analyze and derive insights from meetings. Founded in 2020 and headquartered in San Francisco, it serves over 1,000 customers.

Firebender

San Francisco

Firebender is an AI software company that develops AI coding assistance tools. Founded in 2024, it has raised $3.5 million in funding and currently has a team of three.

Uiflow

San Francisco

Y Combinator is a leading startup accelerator founded in 2005 by Jessica Livingston that runs programs to support startups, including the YC Program, Startup School, and Co-Founder Matching, and provides resources, deals, and ongoing guidan

Greptile

San Francisco

Greptile, a San Francisco AI tooling startup with a six-person team, builds an AI expert on codebases accessible via an API, serving 1,000 software teams; raised $5.3M from Y Combinator, Initialized Capital, SV Angel, and Paul Graham, with

Stainless

San Francisco

✱ Stainless provides robust & polished SDKs for your REST API.They're idiomatic, type-safe, and engineered to feel like handwritten code.API-first companies like OpenAI, Anthropic, Meta, Cloudflare, and Scale use Stainless to generate SDKs

Chroma

San Francisco

Chroma provides data infrastructure for AI, aiming to accelerate useful and creative AI applications, and positions itself as the leading retrieval solution trusted by developers worldwide.

OpenBlock

San Francisco

OpenBlock builds CLI coding agents; its OB-1 ranked #1 on Terminal Bench ahead of Claude Code and Codex highlights leadership in developer tooling and its aim to empower individuals and teams to create and innovate in software development f

Diversion

San Francisco

Diversion is a well-funded, early-stage company building a modern, cloud-native SCM as the basis of the dev stack for developers worldwide, and claims to be the world's first fully cloud-based version management solution for the creative in

Infisical

San Francisco

Infisical is the #1 open-source secret management platform for developers, aiming to make security easier. Based in San Francisco with a remote team, it has raised $3M from Y Combinator and serves customers such as Hugging Face and Delivery

Hex

San Francisco

Hex provides a data analytics platform that makes analytics workflows more powerful, collaborative, and shareable, addressing key pain points in modern data tooling; used by thousands worldwide for its beautiful UI and exceptional flexibili

Replicate

San Francisco

Replicate is a San Francisco-based company focused on open-source AI models and cloud deployment, enabling easy running and hosting of ML models. Founded in 2019, it has a 36-person team and raised $40 million in December 2023.

Confident AI

San Francisco

Confident AI is the leading LLM evaluation platform behind the open-source DeepEval framework; its cloud product brings DeepEval to enterprises, backed by 600k+ monthly downloads, 5.3k+ GitHub stars, 40 million evaluations, and hundreds of

Helium

San Francisco

Helium automatically generates and tests paywalls to improve app conversion. Backed by Y Combinator, Google, and leaders from OpenAI and Uber, the company is positioned in the paywall automation space for apps.

LiteLLM

San Francisco

LiteLLM develops open-source developer tooling for the AI software space, enabling access to multiple LLM APIs. It has raised $1.6M in seed funding from Y Combinator, Gravity Fund, and Pioneer Fund, and reports $7M+ ARR while remaining mean

Unsloth AI

San Francisco

Unsloth AI, a San Francisco–based company, makes custom AI accessible by fixing critical LLM bugs (Gemma, Llama, Phi-4) and conducting open-source RL and fine-tuning; YC S24-backed with investors such as Logan Kilpatrick and Jon Oringer, us

A0.dev

San Francisco

a0.dev is a platform generating custom React Native projects to help mobile developers build apps in days, not weeks. It has launched apps used by hundreds of thousands of users and relies on React Native, TypeScript, Node.js, Express, Next

Idler

San Francisco

Idler builds reinforcement learning coding environments that train AI to code like elite engineers using real-world scenarios. It closed a multimillion-dollar contract with a leading foundation lab and is scaling to power the training data

Emdash

San Francisco

Emdash is an open-source agentic development environment that runs multiple AI coding agents — Claude Code, Codex, Cursor, Gemini, and more — in parallel, each isolated in its own Git worktree, with built-in diff review and PR creation.

Velt

San Francisco

Velt SDK provides JavaScript toolkit to add collaboration features to apps. Founded by former Google engineers who built AR for Search and Maps, it is YC-backed and aims to ship collaboration experiences and boost growth across creative, an

Aviator

San Francisco

Aviator builds engineering productivity supertools that automate mundane developer workflows. YC-backed, well-funded startup counts Doordash, Square, Benchling, Figma, Bosch, and Slack among customers, with investors Elad Gil and Lenny Rach

Seam

San Francisco

Seam provides an API to control a broad range of IoT devices, focusing on door locks and access systems, enabling developers to orchestrate the physical world; it ships millions of devices and is backed by Tiger Global and Root VC.

Memfault

San Francisco

**First IoT reliability platform for debugging, monitoring, OTA updates** Memfault is the first IoT reliability platform that empowers teams to build more robust devices with software at scale. We believe that device reliability engineerin

Okteto

San Francisco

**Cloud Development Environments with one click** At Okteto, we are working hard at creating the next-generation development experience for teams of all sizes. Have you ever seen how long it takes a developer to set up everything they need

RevenueCat

San Francisco

**A simple API for managing in-app subscriptions** RevenueCat is a mobile SDK and API for managing in-app subscriptions We take the sting out of supporting the complicated subscription systems of the App Store and Google Play Store, and he

Nanonets

San Francisco

Nanonets is an AI-driven platform that automates document processing and data extraction using OCR and deep learning, scalable from small deployments to enterprise-grade automation with an API-integrated solution; it counts 35% of Fortune 5

Deepgram

San Francisco

Deepgram is a foundational AI company focused on speech transcription and understanding, building AI for speech. A Y Combinator company and NVIDIA partner, it completed a $72M Series B and says it is most-funded speech AI company at its sta

Same

San Francisco

Same enables anyone to prompt software into existence, March 2025 mission that drew 350,000 signups and seven-figure ARR. Led by Aiden Bai and Nisarg Patel, it develops open-source Million.js and React Scan, in production at Airbnb, Robinho

Mentra

San Francisco

Mentra is building MentraOS, an open-source OS for smart glasses, aiming to own the software stack for the next generation of personal computing and to compete with Apple and Google. Team includes six years in smart glasses and MIT/Tsinghua

SigNoz

San Francisco

SigNoz is an open-source observability platform that helps developers monitor applications and troubleshoot problems, offering an open-source alternative to DataDog and New Relic. It has a strong community (21k GitHub stars, 6k Slack member

Better Auth

San Francisco

Better Auth, founded by Bereket Engida, is a TypeScript authentication framework and infrastructure platform offering user management, analytics, bot/fraud detection, transactional messaging, and session storage; it is open source with a co

BuildBuddy

San Francisco

BuildBuddy was founded to boost developer productivity by democratizing access to world-class engineering tools that are typically reserved for employees of large companies, making them available to everyone.

DeepSource

San Francisco

DeepSource is a unified DevSecOps platform that analyzes code changes to identify and fix security, performance, anti-patterns, and bug risks across every commit and pull request, integrating with GitHub, GitLab, and Bitbucket.

Olive

San Francisco

Olive enables companies to create internal tools by describing their needs in natural language, positioning itself as the fastest way to create internal tools. It has raised a $2.1 million seed round and is scaling its team.

Nango

San Francisco

Nango is a San Francisco-based, remote B2B software company building an open-source platform with a single API for all SaaS integrations. Founded by Robin Guldener and Bastien Beurier, it has YC participation, $2M funding, 300+ production c

Dioxus Labs

San Francisco

Dioxus Labs develops cross-platform apps using Rust and maintains an open-source project competing with Flutter, React Native, and native toolkits. With nearly 20,000 GitHub stars and participation in the GitHub Accelerator, it has gained n

BootLoop

San Francisco

BootLoop specializes in hardware and firmware reliability for advanced technologies, enabling rapid development and testing for rockets, fusion power, supersonic aircraft, and medical devices; founded by Chris Markus (SpaceX firmware/Starsh

Vly.ai

San Francisco

vly.ai is building an AI full-stack development platform that can architect, build, deploy, and iterate on complete applications autonomously, aiming to replace most full-stack work within a year and competing with Replit, Lovable, and bolt

Morph

San Francisco

MorphLLM develops Fast Apply models for code editing AI, claiming the fastest LLM code-editing inference engine, delivering 10,500 tokens per second per request on Nvidia hardware. Its stack enables high-throughput AI workflows for coding a

Orchids

San Francisco

Orchids is an AI app and site builder, one of the fastest-growing in its market, leveraging cutting-edge AI to transform how apps and websites are built. It aspires to be the last tool people need to deploy apps and sites.

Cua

San Francisco

Cua builds infrastructure for general AI agents to safely use computers and apps. It offers an open-source framework and cloud sandboxed container platform, a seed round, 9k+ GitHub stars in four months, and a research-backed blueprint for

Promptless

San Francisco

Promptless builds AI teammates that integrate with users’ existing workflows, serving startups and Fortune 500 enterprises. It ranked among the top W25 by revenue; small founding team has led startups, published LLM research, and graduated

Vapi

San Francisco

Vapi provides a configurable platform to deploy voice agents. Aiming to make voice humanity’s default interface, it's grown to 400,000 developers in 20 months and raised $20M in Series A led by Bessemer Venture Partners, Canadian founders J

Medplum

San Francisco

Medplum is an open-source, API-first electronic health record (EHR) platform that increases access to and usefulness of medical data, used by major digital health and life sciences companies to build medical applications.

Attune

San Francisco

Attune builds developer tools for a post-AI world, delivering tooling for developers operating in a post-AI context and positioning itself as a provider in the evolving developer tools market. It prepares developers for the next era of soft

Amplitude

San Francisco

Amplitude is a San Francisco-based digital analytics company founded in 2012 by Spenser Skates (CEO) and Curtis Liu (CTO). It went public in 2021, serves over 3,000 paying customers, and focuses on product analytics to help organizations bu

Floot

San Francisco

Floot builds an AI-first software foundation enabling non-coders to build and deploy full-stack web apps. It grew to 600+ customers after Y Combinator and features founders from Retool and AWS, with a CTO who bootstrapped a SaaS to $5M+ ARR

Capy

San Francisco

Scout is an AI-native software engineering agent that operates asynchronously on its own VM and tackles long-horizon tasks on large codebases.

Relace

San Francisco

Relace focuses on models and infrastructure for coding agents, defining its core offerings around coding-agent technology.

Stacksync

San Francisco

Stacksync provides real-time, two-way data synchronization between CRMs and databases, serving engineers and RevOps teams. Founded by Ruben Burdin and Alexis Favre, the company focuses on data movement and enterprise integration.

Julius

San Francisco

Julius is San Francisco AI lab aiming to enable one billion people to become software creators. It writes 1 million lines of code every 36 hours and generates 3 million visualizations for more than 1 million users.

Relari

San Francisco

Relari is building infrastructure for trustworthy AI agents in the Software 3.0 era, behind Nuvi.dev, and has developed open-source frameworks Agent Contract and continuous-eval to help ensure AI systems behave as intended.

PgDog

San Francisco

PgDog builds scaling tools for PostgreSQL, including load balancing and sharding, aiming to make PostgreSQL the database you’ll need. The Rust-based platform shows compatibility with integration tests across 7+ languages and Postgres driver

Nozomio

San Francisco

Nozomio builds context-augmentation infrastructure for AI agents, indexing codebases, documentation, and external sources to provide agents with expanded knowledge. It claims this boosts performance by 27% and emphasizes fast shipping and r

Helicone

San Francisco

Helicone is an open-source observability platform for LLM applications, delivering monitoring, optimization, and reliability tools to productionize AI systems. With ~4,000 GitHub stars, a thriving community, 20% MoM growth, and SOC 2 and GD

Embedder

San Francisco

Embedder develops a coding agent for firmware development in embedded systems, enabling writing and testing firmware on real hardware with connections to physical tools. It indexes hardware documentation to provide hardware-specific context

Emergent

San Francisco

Emergent enables anyone to build production software by describing requirements in natural language. Founded by Mukund Jha and Madhav Jha, it attracted 700,000 users and $10M ARR in two months, among fastest-growing AI companies, serving en

Synth

San Francisco

Synth helps agent developers maintain and improve their AI software by identifying problems and fixing them with changes to scaffolding code, prompts, and models. It builds Research Engineering Agents and focuses on advancing AI agent devel

Woz

San Francisco

Woz helps non-technical founders turn ideas into scalable software by combining expert engineering, business tools, and go-to-market support, bridging AI-generated code with real-world growth and accelerating the path from concept to market

Benchify

San Francisco

Benchify builds a reliability layer for AI-generated code, ensuring dynamic builds and self-healing pipelines so AI-powered software runs reliably and securely without human babysitting. Founded by Juan Castaño and Max von Hippel.

Conductor

San Francisco

Conductor, based in San Francisco, has a three-person in-person team including Omid and is building the first AI orchestrator; backed by Silicon Valley investors to sustain operations through rough patches.

CodeAnt AI

San Francisco

CodeAnt AI, a Y Combinator-backed startup in code quality and security, uses AI-driven and deterministic fixes to improve code quality and safety, earning trust from unicorns and public companies and support from top Silicon Valley investor

BrowserOS

San Francisco

BrowserOS develops an open-source agentic browser to host a generalist AI agent that performs tasks in the browser. It invites collaboration on building browser agents and training Large Action Models, positioning itself as a developer of b