Y Combinator Fall 2026 (F26) Companies

0.security develops AI agents that autonomously test software for vulnerabilities, verify them, and deploy fixes across the full stack from web apps to the Linux kernel. It serves developer teams, enterprises, defense organizations, and critical infrastructure providers through a cloud product and an open-source offensive security harness.

1 investor

Acyclic Labs runs agent swarms that break a task into parallel work across many sandboxed agents and merge their outputs into a single result, cutting the wall-clock time of long agentic workflows. Accessible via CLI, dashboard, or coding agents over MCP, it supports user-supplied model keys and self-hosted sandboxes atop an open-source harness, serving coding, research, and data workloads.

1 investor

Adside is an advertising tool that tracks competitors' live ads and monitors market chatter on X, Reddit, and G2, identifying relevant competitors in a user's niche. It consolidates ad management across Google, Meta, LinkedIn, Reddit, and Twitter into one platform, which teams can run themselves or have managed by an expert from Adside's network.

2 investors

Agent 37 provides persistent, pre-configured sandboxes for running AI agents such as Claude Code and Hermes, retaining files, code, and settings between sessions. It offers usage-based compute billing, single-command backend setup, and connections to tools like Slack, Gmail, and GitHub for developers deploying autonomous agents.

1 investor

Agent Relay provides infrastructure for software teams to coordinate coding agents such as Claude Code, Codex, OpenCode, and custom agents, offering shared messaging, session history, and integrations with tools like GitHub, Linear, and Slack. It lets teams monitor agent activity, run resumable workflows, and intervene manually, with deployment options in the cloud, locally, or on their own hardware.

2 investors

Ageospatial provides an AI service that analyzes satellite and street-level imagery, maps, public records, and insurers' own data to assess property risk remotely without physical inspections. It serves insurance carriers and MGAs, supporting their underwriting, claims, and pricing teams.

1 investor

Aikido Technologies develops technologies for clean energy and intelligence infrastructure to support a sustainable future. The company focuses on engineering solutions for energy systems and related infrastructure.

2 investors

Altair Health provides an AI-driven medical billing service for independent medical practices, handling the full billing process and submitting claims to insurers while human billers manage exceptions. It uses a theorem prover that checks each billing action against formalized insurer policies before claims are submitted, and learns insurer payment behavior over time to predict payments, denials, and delays.

1 investor

Antimattr is building voice-first interfaces focused on memory and voice productivity, positioned as an ecosystem of products for natural human-machine interaction. Its first product, Project Mnemosyne, is scheduled to begin shipping in Q4 2026.

1 investor

Antropi Robotics develops autonomous CNC factories that automate machining processes to accelerate hardware production. The company operates in the industrial robotics and manufacturing automation sector.

1 investor

AnyAlpha is a trading platform that converts a user's trading idea into an automated agent, building it on institutional data, backtesting it against historical data, and executing trades live across multiple exchanges. It initially focuses on prediction markets, with plans to expand to additional asset classes.

1 investor

Applied Kinetics develops AI agents that manage supplier coordination for energy and data center construction projects, tracking equipment approvals, delivery dates, and delays. It serves project teams building out energy and data center infrastructure.

1 investor

Archangel Health provides infrastructure to post-train and evaluate medical AI, including reinforcement learning environments built inside de-identified electronic health records, physician-verified training data, and benchmarks for clinical reasoning. It serves frontier AI labs, medical AI companies, and health systems looking to post-train open-source models on their own data.

1 investor

Archgen Labs develops AI-powered electronic design automation (EDA) tools for 3D semiconductor design, including a GPU-accelerated placement engine, a thermal analysis tool, and an AI agent that automates placement, routing, design-rule fixes, and timing closure. Its software helps chip engineers jointly optimize placement, timing, and temperature when designing faster, more power-efficient stacked 3D chips.

1 investor

Armorer Labs provides continuous security verification for AI agents, testing them with simulated attacks, generating verified fixes, and monitoring each agent action in production to detect and block threats like prompt injection, goal hijacking, and data leaks. It serves companies in regulated industries that are deploying their own AI agents.

1 investor

Asakana uses AI to convert restaurant orders sent by email, text, and photo into entries in a food distributor's ERP system, flagging unclear items for human review. It serves food distributors, currently seafood distributors in the US, as an order-entry automation tool.

1 investor

Ascenix provides software for long-term care and nursing facilities that captures, classifies and tracks resident incidents such as falls, pressure injuries, hydration shortfalls and behavioral events across units. The system consolidates documented triggers, repositioning and wound assessments to support care teams in monitoring resident safety.

1 investor

Asim develops technology that helps robots operate safely in real-world environments, serving companies building and deploying robotic systems.

1 investor

Aucert provides AI agents that automatically test mobile apps, covering functional QA, accessibility, and Google Play and App Store policy compliance, and integrates with agentic coding workflows so issues can be fixed within the same development loop. It serves mobile app development teams looking to speed up release testing.

1 investor

Audora converts books and stories into audiobooks by identifying each speaker and assigning a distinct voice to every character alongside the narrator. Starting with fanfiction, it serves readers who want character-specific, consistent voices in their audiobook listening.

1 investor

Aviern develops fixed-wing unmanned aircraft that launch, fly, and land autonomously from unattended docks to inspect infrastructure corridors, using onboard perception to detect leaks, encroachments, and vegetation risk. Sold as a per-mile service starting with regulated pipeline patrol, it serves operators of pipelines, power grids, rail, borders, and military bases in the geospatial intelligence and infrastructure monitoring sector.

1 investor

Axonnic develops wearable EMG technology that records human muscle activity—including intent, effort, and force—as people perform physical tasks, producing training data for AI models used in dexterous robotics. The company targets robotics developers and also applies its approach to human–computer interaction based on movement and muscle signals.

2 investors

Blinka offers USD accounts and a global Visa Infinite card with no FX markup, letting businesses receive USD via ACH, wire, or onchain transfers and accept local COP deposits through PSE. It also provides invoicing, payment collection, vendor management, and transaction organization tools, with a focus on cross-border business banking including Colombia.

2 investors

Ascii offers preconfigured Ubuntu cloud virtual machines, called boxes, that come with a desktop, browser, common programming languages, Docker, snapshots, and management tools via CLI, SDK, and API. The service is aimed at running AI agents at scale for tasks such as coding and knowledge work including legal, research, reporting, and auditing.

1 investor