VC and Accelerator Portfolio List Builder

Turn a venture capital firm or an accelerator into a list of the companies it backs. Enter Y Combinator, a built in fund such as a16z, Sequoia, or Accel, or the URL of any investor's portfolio page. You get one flat row per portfolio company with its name, domain, website, a short description, and the stage, batch, or status where the source gives it. Rows export to CSV or drop into a Clay table, a CRM import, or an enrichment step.

Features

• Y Combinator by batch. Reads the public Y Combinator company directory, filtered by batch (S24, W25, or Summer 2024), industry, region, status, or search words, with team size, location, and industries on every row.
• Built in funds and accelerators. Andreessen Horowitz (a16z), Sequoia Capital, Accel, Index Ventures, Founders Fund, Greylock, Lightspeed Venture Partners, Khosla Ventures, First Round Capital, Techstars, and Antler, each measured on 2026-10-21.
• Any portfolio page. Paste a portfolio page URL. The actor reads the company list from the page's own data, from its links to company websites, or, when the page links only to its own per company pages, by opening those pages to read each company's website.
• Only new companies. On a schedule, a company an earlier run returned is skipped and not charged, so each run returns new portfolio additions.
• One summary row per source. A free row per investor says how many companies were found, how they were read, and why a source returned nothing.
• Cost guards. Max companies per source, max company pages per source, and a max charge per run.

How sources are read

Every page is fetched directly from the investor's own site, and the site's robots.txt is read first and obeyed: a page it disallows is not fetched, and the summary row says so. A site that refuses a direct request is read through the Apify proxy. Y Combinator is read from its public company directory: the directory page publishes the settings of its own public search index, and the actor queries that index the way the page does. No account, no API key, and no other developer's actor are used.

Measured on 2026-10-21 with 40 companies per source:

Source	Read from	Companies	With a domain	With stage or status
Y Combinator	yc directory	40	40	40
Andreessen Horowitz	embedded json	40	40	0
Sequoia Capital	detail pages	21	16	0
Accel	embedded json	40	40	0
Index Ventures	detail pages	40	39	0
Founders Fund	detail pages	40	0	0
Greylock	detail pages	40	40	12
Lightspeed Venture Partners	detail pages	40	38	36
Khosla Ventures	page links	40	40	29
First Round Capital	embedded json	40	40	10
Techstars	page links	30	30	11
Antler	page links	40	40	0
GV	none	0	0	0
500 Global	none	0	0	0

GV and 500 Global draw their portfolio lists with script after the page loads, so a page read finds no companies; the summary row says so. Founders Fund company pages link every company to the same website, so its rows carry the company name with no domain, free.

Input

Field	Type	Default	What it does
investors	array	Y Combinator	Built in names or portfolio page URLs, up to 25
yc_batches	array		Y Combinator batches, for example S24, W25, Summer 2024
yc_industries	array		Y Combinator industries, for example B2B, Fintech
yc_regions	array		Y Combinator regions, for example Europe
yc_status	array		Any of active, acquired, public, inactive
yc_query	string		Words to search the Y Combinator directory for
max_companies_per_source	integer	500	Company rows per source, up to 10,000
open_company_pages	boolean	true	Open per company pages when the portfolio page links only to them
max_detail_pages	integer	200	Company pages opened per source
only_new	boolean	false	Skip companies an earlier run returned for the same source (free)
state_key	string		Name for the only new companies memory
max_charge_usd	string		Stop before a charge that would pass this amount
proxy_mode	string	auto	auto or direct. A reliability setting; it does not change what you pay

Output

Field	Type	Example
row_type	string	company or source_summary
source_name	string	Y Combinator
source_type	string	accelerator, vc_fund, or unknown
source_url	string	https://www.ycombinator.com/companies
adapter	string	yc_directory, embedded_json, page_links, or detail_pages
company_name	string	Outerport
company_domain	string	outerport.com
company_url	string	https://outerport.com
description	string	Design automation for industrial electrical controls
stage	string	early, seed, series b, when the source gives it
status	string	active, acquired, public, inactive, when the source gives it
batch	string	Summer 2024 (Y Combinator)
industries	array	["B2B"] (Y Combinator)
location	string	San Francisco, CA, USA (Y Combinator)
team_size	integer	4 (Y Combinator)
source_profile_url	string	the company's page on the investor site
is_new	boolean	true with Only new companies on
companies_found, companies_delivered, pages_read, robots_note	source summary only	counts and notes
row_status	string	ok, no_results, no_change, partial, blocked, or error
error_reason	string	why a source summary is not ok
billable_events_json	string	{"company-row":1}, or {} for a free row
checked_at	string	when the row was written

Pricing

Pay per event. You pay for company rows that carry a company domain, and for the run start. Source summary rows, rows with no domain, and companies already delivered with Only new companies on are free.

Event	Free plan	Bronze	Silver	Gold
company-row, one portfolio company with a domain	$0.007	$0.00665	$0.0063	$0.00595
apify-actor-start, once per run (one per GB of memory; the default 256 MB is one)	$0.0025	$0.0025	$0.0025	$0.0025

Per 1,000 company rows: $7.00 on the free plan, $5.95 on Gold.

Free plan cap: 1.50 USD of evaluation a month, about 214 company rows. Any paid Apify plan removes the cap, and it resets on the 1st. The run stops before a charge that passes your maximum charge per run in Apify or your max_charge_usd.

Mamba Labs pays the platform costs of your run, Apify proxy traffic included.

Usage examples

Apify Console or API.

{
  "investors": ["Y Combinator", "Accel", "https://example.vc/portfolio"],
  "yc_batches": ["S24", "W25"],
  "max_companies_per_source": 500
}

Read the rows with GET https://api.apify.com/v2/datasets/{datasetId}/items.

Clay. Run the actor from a Clay HTTP column or the Apify integration and map the flat columns. Every input accepts strings, and a list can be one comma separated string.

MCP. The Mamba Labs MCP server @mambalabsdev/mcp-vc-accelerator-portfolio-list-builder exposes the tool build_portfolio_list to Claude and other MCP clients.

Error handling

Case	What you get
A name that is not built in	A free summary row, row_status error, asking for the portfolio page URL
robots.txt disallows the page	A free summary row, row_status blocked, with the note; the page is not fetched
The site refuses a direct request	The page is read through the Apify proxy
The page draws its list with script	A free summary row, row_status no_results, saying so
No new companies with Only new companies on	A free summary row, row_status no_change

Limitations

• A portfolio page that loads its list with script after the page opens returns no companies. The actor reads page HTML, not a browser.
• Some funds show only a selection of companies on their portfolio page. The actor returns what the page lists, and Techstars and Sequoia pages list a selection.
• Stage and status come only from what the source labels. Many fund pages give neither, and the columns stay empty.
• Domains are read from the source's own website links and cleaned (lowercase, no www, no path). They are not checked against a company register.
• A site that changes its page layout can drop rows until the actor is updated; the summary row then reads no_results.

Mamba Labs actor suite

Actor	Actor ID
Account Hiring Watch	gRAZA5WBi1r6L0gy7
Agent Accessibility Auditor	anxbRv0lKrpQ1pnua
Agent to Brokerage Resolver	ePRRGLxOGyaVHO4dI
AI Tooling Detector	EwkHhmqiuJgRoVEbE
B2B Reddit Conversation Monitor	SoDryzzsjmY3SsiyG
Bluesky Brand Presence Mapper	eLpxzP4IuXznlFVND
Career Change Signal Engine	vX2Yga1a6wGaXaP14
Company Change Event Feed	oX44rS0fkEJ3rXLWe
Company Contact Details Extractor	4mMncKaJykiq94grz
Company Discovery List Builder	jch0HdaZnpbMqlcGS
Company Firmographic Enricher	YlUtLWjfPpqykmB8g
Company Funding Record	OFS4Mt1gyYNtGfUbE
Company Identity Resolver	lr8fTRAmZCBZmuwwh
Company Social Presence Mapper	4k6CCemkgBDz18m2h
Contact Classifier	0lGSeYJmniXhGANnO
Cookie Consent Audit	TrKyOS0KBoGC35nbr
Domain Deliverability Checker	0tVgxI7A6o9jMlxmc
Domain to LinkedIn URL Resolver	3HtnSaqPHOg1Qg5gx
Ecommerce Platform Profiler	5G2NeYjBbQTjaTn9L
Event Presence Index	WLhMy8fMDgsxdYxv5
Expert Witness Directory	LIpwlgfE3LaQBaXd4
Funding and Press Signal Scanner	FS13X6dhQVgX3XOM6
GitHub Organization Signal Scanner	ahF8RRpv5mzPao5CN
Google Ads Transparency Monitor	1eOwxhBVxzvOXAm4s
Government Contract Award Monitor	zhEtllASykOcx9hJ8
GTM Hiring Signal Scraper	D7O1SA2EqwHGsGr1P
GTM Signals Aggregator	xKdRfnfFNkdMpFuNs
ICP Fit Scorer	W161DT8W4kW55dMFh
Influencer Change Monitor	d2VVgahNL6UmcLkhg
Influencer Finder	tpkedmloIIWtXx6sg
Influencer Lead List Builder	KnmByszcv135yM30G
Influencer Profile Scraper	EqEnklDVMIcB1V499
Influencer Talent Agency Lookup	zCuX4Mgyg6JvXgGzd
Instagram Facebook Brand Presence Mapper	HXh65I0JBjPsunbY8
Integration and Marketplace Presence Mapper	V0guNuvM85Q61f2gj
Job Board Keyword Signal Scanner	4DvqpvhMR74NLcDDY
Job Change Tracker	L8UbEmMJC1XYPSZOb
Job Posting Monitor	QCfICD9kOPiOdj5iI
Legal Entity Resolver	KHFyPCDIx7CyqULYm
Link in Bio Scraper and Newsletter Detector	OorucdheTIgu7RFzK
LinkedIn Company Page Mapper	zOPm6A9JEhUGcIdFW
LinkedIn Post Tracker	oiGLNPuaf5BRaz9K5
Meta Ad Library Monitor	J1GWlSXfSGU3u8Wng
Mobile Phone Waterfall	6OOgPktf7RIa5XCOP
New Hire Finder	cKuc38p4nYHNF3IW8
Outbound Stack Detector	v43UJC8r7qW7cBSTG
Page Finder and Extractor	TpurgcOZbVnknlaiC
People Finder & Email Verifier	LEgloG7tWgQl4o6TD
Person Social Footprint Mapper	jfQXa2zW9FHCJot9K
Pinterest Brand Presence Mapper	d1HvjZfKhgvWsoEwn
Prospect Engine	q9rT6v64nUJdPexOQ
Publishing Frequency Tracker	TbLwaUUATdYb6wp4N
Reddit Brand Presence Mapper	pKQZmDaT70SEb54bZ
Reporting Window Finder	uINxR7a1IW8qUTRUX
Sequencer Lead Push	0Jv27VeWM5tSZQs9x
Team Page People Extractor	j8a9zX0k4mNbvDbWK
Tech Stack Signal Detector	qyd7nNyqFPelQViBx
TikTok Brand Presence Mapper	fco8FvoJcSafbeyd1
Trustpilot Reputation Enricher	3lIqfCt61j4hqE1xz
WCAG Accessibility Audit	P3jBj3FRghKEhX52z
Website Traffic Rank Estimator	GnOFUzlNVIoXgeJjH
Work Email Waterfall	OT6xqTFThC0Rjf7Zj
Workplace Program Detector	Li6pPDhqbdzFz3h7G
X Brand Presence Mapper	oLOgadhHUkNAyDA3w
YouTube Channel Stats Extractor	6hSpD3kd2s2IQ4VSs
Website Phrase and Business Model Classifier	CBuZ9k7sRwBeiKiCS
Competitor Price, Stock, and Changelog Monitor	yxdgCbUQ4PYQWwRNU
Open Tender and RFP Finder	kPTGz6t6TFoUUyfaO
New Company Registrations Feed	g2WfZhWvCtc57g2Jo
Manufacturer and Supplier Finder	Qcsdmd0lUfPzVkonh
Local Rank and Map Pack Tracker	gv0kyHGDIg8XscclB
Company Headcount Estimator	aHC4GROnNt6kfZe5r
Person LinkedIn URL Resolver	ssuyPV8LnEsL8qbnb
Personal Email to Company Resolver	AefT5Ye6YNPFQwJBf
Partner and Member Directory Extractor	ZX0XJPPUvnFJxeC1a
Local Business Lead Builder	qMN97aoHhsAS5bznV
Ecommerce Store Discovery	PeHu4sLyFvQHXUUrX
Contractor License Lookup	WBYK3CPI2kdeq4bP1
Sequencer Event Poller	S6s8Rjd61tGdrMRk4
Lookalike Company Finder	e2O426WBAbLLQL4Z2
Public Feature Board and Roadmap Monitor	rcHF5gj5r2Vqnry35
Podcast Guest and Host Finder	o2MGSvgbSLeeXOsIo
Newsletter Sponsor Tracker	qSwpqxD1TiPZpLQHv

MCP servers for the suite are published under the npm scope @mambalabsdev.

Built by Mamba Labs.