Stealth Startup Spy #215 - Y Combinator W25

An early look at the Y Combinator Winter 2025 batch weeks before demo day! Full list available for download.

We are giving you early access to the Y Combinator Winter 2025 batch.

Every time a YC founder leaves any clues (publicly or privately) that they have joined an upcoming batch, we get an instant alert via Slack, and our system logs it.

The result: a curated, up-to-the-minute dataset of stealth and recently revealed companies that will feature on Demo Day.

Here are some of the trends from the upcoming Y Combinator Winter 2025 batch.

1. Agent-Driven Automation

• Caseflood – Replaces law firm admin with AI agents

• careCycle – AI voice teams for Medicare and ACA distributors

• Calltree AI – Analyzes call center workflows to cut costs

• Tally – AI agents automate accounting, tax, and audit

• Bluebook – AI accounting agents to serve more clients

• Toothy AI – Automates back-office operations for dental clinics

• Agentin AI – Agents that move data and take actions across enterprise systems

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2. AI Infrastructure & Data

• Asteroid – Runtime supervision for AI agents (guardrails + human oversight)

• Confident AI – LLM evaluation, benchmarking, and red-teaming

• TrainLoop – Improves reasoning models with minimal developer effort

• Augento – Fine-tuning as a service for struggling AI agents

• Exla – Aggressive model quantization to reduce memory usage

• Mastra – All-in-one AI dev toolkit (workflows, RAG, evals)

• Gulp – Simplified real-time data pipelines for fraud, recommendations, etc.

• AfterQuery – High-quality expert datasets for fine-tuning and RLHF

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3. Generative AI Across Voice/Video

• Leaping AI – Voice AI agents that handle up to 70% of calls end-to-end

• Pickle – Lifelike AI clones for video calls, lip-sync in real time

• Pinch – Real-time audio translation with synced lip movements

• Mosaic – Natural-language-driven video editing

• Dollyglot – Studio-quality voice cloning in any language

• Riviera – AI voice agents for hotel front desks and reservations

• Opine – Social media app to create custom AI video characters

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4. Vertical AI in Regulated Markets

• Archon – Cuts FedRAMP compliance from 16 months to 6

• Candor – Auto-drafts proposals for defense, energy, biotech funding

• Maive – Automates aerospace compliance paperwork on the shop floor

• Harbera – AI for continuous physician credentialing

• HealthKey – Matches patient EHR data with clinical trial eligibility

• Vantel – AI software platform for commercial insurance brokers

• Rada – Automates insurance calls for healthcare providers

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5. Deep Tech & Robotics

• Red Barn Robotics – Autonomous weed removal to boost crop yields

• Pave Robotics – Robots that seal cracks in asphalt 24/7

• Revise Robotics – Automating electronics refurbishment and resale

• Maritime Fusion – High-temperature superconducting fusion reactors for marine use

• Inversion Semiconductor – Next-gen chip fabrication machine, 15× faster

• Orbital Operations – High-thrust, refuelable orbital vehicles

• Splash – Autonomous surface vessels for national security

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6. Biotech & Medical

• Exin Therapeutics – Precision genetic therapy for neurological disorders

• Uncommon Therapeutics – Multi-therapeutic platform tackling high-value diseases

• Amby Health – AI-powered EMS workflow automation

• Mecha Health – Transparent, AI-driven radiology reporting

• Cenote – AI automates medical practice back-office tasks

• Vetnio – Reduces vet admin work by 40% with AI

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7. Productivity & No-Code

• a0.dev – Generates custom React Native apps in days

• Woz – AI platform to build and grow software businesses (no coding required)

• Onlook – Open-source Cursor for Designers; edit live websites instantly

• Nitrode – AI-assisted game creation and launch

• Promptless – Automatically updates your public documentation

• Quantstruct – AI-generated changelogs and implementation guides

• Sammy Labs – AI that explores your app like a real user (QA automation)

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8. Classic B2B SaaS + AI

• Stamp – AI-powered email client for automated sorting and replies

• Ergo – CRM that auto-updates from calls and emails

• Overstand – Summaries of customer communications for busy execs

• Spott – Next-gen ATS & CRM for recruitment agencies

• Sammy – AI-based QA automation for apps

• Mercura – AI-assisted quoting from BOMs and spec sheets

• Solidroad – QA and coaching for live call center reps

• Opine – Social media for AI avatars and voice-enabled creations

FYI - This dataset is a 3-sheet report with full founder profiles and emails, company details and this full market map. (Limit is 50 downloads)

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Here’s some of the stealth activity from this batch (full list available here)

🔮YCW25 Startups Spotted Early

We love tracking early-stage startups before they hit the spotlight, and this YC batch proves it: several companies we featured months ago just made it into Y Combinator.

HealthKey

🕒 Featured 17 months before YC

Helping doctor’s offices generate revenue by using AI to match patients with clinical trials. Their platform automates patient prescreening, unlocking new revenue streams from Big Pharma.

Team: Josh Sabol

Connect on: LinkedIn or Email

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Leaping AI

🕒 Featured 12 months before YC

Powering voice AI agents that automate complex, high-volume contact center operations. Their human-like voice AI agents automate up to 70% of customer support calls—all while maintaining a 90% customer satisfaction rate.

Team: Shraey Bhatia, Arkadiy Telegin, Kevin Wu

Connect on: LinkedIn or Email

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Overstand

🕒 Featured 6 months before YC

A customer insights platform that transforms Slack, emails, WhatsApp, and call transcripts into actionable insights—helping founders stay connected, spot trends, and drive impact.

Team: Derrick Cheng, Mihir Patil, Senta Knuth

Connect on: LinkedIn or Email

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General Trajectory

🕒 Featured 3 months before YC

Training vision-language-action (VLA) models to bring AI to the physical world, automating tasks like palletization, sorting, picking, and packing.

Team: Joshua Belofsky, Jack Armstrong

Connect on: LinkedIn or Email

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Y Combinator’s Winter 2025 Batch has their Demo Day on March 12th, 2025 so this is your early look at all of the startups participating in this event.

Most of these founders and companies are not yet listed in the YC directory and we will constantly update the dataset as founders continue to exit stealth.

Notice: This link will be taken down at 50 downloads and before 11:59pm EST on Friday of next week....

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Stay Stealthy,

Drake

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Stealth Startup Spy is a data-driven newsletter for investors, journalists and tech enthusiasts interested in uncovering the next big move for key talent, real-time stealth company launches and technology advancements not in plain sight. We leverage the technology built at Gravity to shine a light on the hidden world of stealth startups.