Y Combinator Summer 2026 (S26) Companies

Hilstart provides an AI agent and a hardware interface device called Tracer that automate electronics board bring-up, firmware development, and design validation on real hardware. It serves hardware engineering teams, generating and running approved test plans, driving instruments, and writing results back to their tracker via API, usable in the cloud or from the user's own environment.

1 investor

Hop Aero develops rocket-based cargo delivery systems designed to transport supplies to remote or contested locations at high speeds, primarily serving U.S. military and allied defense applications.

4 investors

Hoplite provides infrastructure for deploying and managing software factories in cloud environments.

3 investors

Hubble provides an intelligence layer for patient information, reaching EHRs, payers, and patient records through APIs, browser, and voice to return a single normalized record with source traceability and audit trails. It offers data infrastructure for digital health companies and a no-code workflow studio for operations teams automating manual tasks.

1 investor

Hyperprobe provides an SDK that enables AI coding agents to capture runtime state from running services for production debugging. The platform allows developers to set live breakpoints and inspect variable values without pausing threads or redeploying code, working with tools like Cursor, Claude Code, and Codex.

2 investors

Illume Labs aggregates data from wearables, blood tests, and genomic sequencing to deliver personalized health insights via text message and conversational AI, helping users understand changes in their health metrics and receive actionable recommendations.

2 investors

IMPACT builds a containerized counter-drone defense system that autonomously detects, launches, and intercepts hostile drones, pairing two interceptors: HUNTER for close-range low-altitude threats and SABLE for fast, long-range movers. It targets protection of high-value sites such as data centers, power substations and plants, and airports.

2 investors

Induction Labs is a research lab developing foundation models designed to learn from their own observations and update over time, with the goal of scaling curiosity-driven artificial intelligence toward superintelligence. It positions itself in the AI research and foundation model space.

3 investors

Inkbox provides an identity layer for AI agents, enabling them to have email, phone, iMessage, and internet addresses for communication and interaction.

4 investors

Instance Labs provides verification software that evaluates whether robots have successfully completed assigned tasks from camera footage. The platform helps robotics companies validate training data and accelerate policy development by analyzing raw video episodes and returning success verdicts with evidence.

2 investors

Insurf provides a managed workflow platform for healthcare providers to prepare and submit prior authorization requests and denial appeals. The platform handles source-cited drafting, physician review coordination, and submission tracking, serving Medicare Advantage and other health insurance programs.

2 investors

Isengard Industries manufactures production systems that enable allied nations to domestically produce precision-strike and counter-unmanned aircraft systems at scale and lower cost than traditional defense contractors.

3 investors

Jcode is an open-source terminal coding agent written in Rust, designed for low memory use and fast startup so developers can run many concurrent agent sessions. It includes features such as self-modifying source code, background task tools, semantic memory, and its own uncontaminatable coding benchmarks.

1 investor

Kara engineers single-crystal diamond, handling growth in its own reactors as well as processing and characterization in-house. Its diamond materials target thermal management, power electronics, quantum sensing, photonics, quantum networks, and characterized research substrates.

4 investors

Kebra captures activity from physical field operations, builds a live "operating memory" of that context, and deploys AI agents to automate follow-on work such as back-office tasks. It targets teams doing physical work around equipment and job sites, integrating with field service tools like ServiceTitan.

3 investors

Lamb Labs develops custom silicon chips and a post-training technique that converts existing language models to a diffusion-based architecture for faster AI inference at lower power. It targets developers and companies running large language model workloads in the AI hardware and infrastructure space.

5 investors

Last Accounting Company (LAC) offers a combined accounting service and AI platform, using its agent "Björn" to automate manual bookkeeping while human accountants review the results, replacing tools like Procountor, Fennoa, and Netvisor. It handles bookkeeping, invoices, payroll, VAT and tax filings, monthly closes, and financial statements for startups and SMBs, with data sources connecting into its general ledger and accessible via an MCP server for AI agents.</parameter> <parameter name="founders">[]

3 investors

LATO conducts commercial diligence for investors by sourcing and interviewing domain experts and customers, then combining interview data with public and proprietary documents to create market simulations. The platform helps investors research companies and markets to inform investment decisions.

3 investors

LemonLime is an AI tool that automatically finds sales leads, drafts outreach emails, and creates branded marketing content for a company overnight, leaving the user to review and send. It targets businesses looking to automate their sales and marketing efforts.

2 investors

LevoCred provides AI-powered software for managing structured credit operations, serving credit funds and loan originators. The platform automates loan analysis, compliance monitoring, and report generation workflows.

1 investor

Libra Robotics builds autonomous robots for solar farm installation at utility-scale and commercial projects. The company serves electrical contractors, equipment manufacturers, and solar project developers.

1 investor

Litmus is a hiring platform that evaluates software engineers through practical assessments aligned with how modern engineering teams actually work, replacing traditional interview processes.

2 investors

Justinian is an AI company that develops government affairs software to help companies monitor regulations, lobby policymakers, and win government contracts. The company rebuilds partnerships between government and industry solving critical problems.

5 investors

Luca IQ is a tax preparation platform for accounting firms and CPAs that handles the workflow from client intake and document collection through preparation, review, e-signature, delivery, and IRS e-filing. It structures source documents and provides an audit trail so every field traces back to its source, offered via a single API.

3 investors