Live:108,361 newsletters522,292 articles8,384 topics
Newsletter data for buyers, researchers and AI agents
Search and monitor 108K+ newsletters across Substack, beehiiv, LinkedIn, Kit, Ghost and custom domains. Get alerted when your company, competitors or market show up in an issue, see which brands sponsor which newsletters, and pull newsletters, sponsors and the companies, people and topics they mention straight into your own tools over a REST API or MCP.
No credit card required · 7 days of Pro
Substack · beehiiv · LinkedIn · Kit · Ghost · Custom newsletters
Search
Explore Newsletter Ecosystem
Discover publications, articles, people, brands, and signals across the newsletter ecosystem.
Try
Live from the index
Every newsletter, with the intelligence that matters.
Who each newsletter is written for, how actively it publishes, and which brands sponsor it. This is live data.
beehiiv · Several times a week · Developer tools · AI agents
Likely audience · Product managers
Sponsors ·
Activity · 58 posts in the last 90 days · last post today
substack · Several times a week · AI agents · Developer tools
Likely audience · CTOs
Sponsors · None detected recently
Activity · 31 posts in the last 90 days · last post 11 days ago
beehiiv · Several times a week · AI agents · Investment strategy
Likely audience · Investors
Sponsors · None detected recently
Activity · 50 posts in the last 90 days · last post 7 days ago
beehiiv · Weekly · Developer tools · AI Agents
Likely audience · AI developers
Sponsors ·
Activity · 12 posts in the last 90 days · last post 2 days ago
Product
One index, four ways in: the app, alerts, the API and MCP.
Newsletter search
Search Substack, beehiiv and independent newsletters by topic, company, person or keyword. Compare audience, cadence and momentum, and save a shortlist.
Learn moreSponsor intelligence
See which brands sponsor which newsletters, how often and how recently. Find newsletters your competitors buy, and brands that just started sponsoring.
Learn moreAlerts & monitoring
Get alerted when a newsletter mentions your company, executives, competitors or a topic you track. Daily or hourly digests with the newsletter, issue and date.
Learn moreREST API
A REST API for newsletter data: search newsletters, articles and entities, read publication profiles and sponsor history. OpenAPI 3.1, API keys, per-plan quotas.
Learn moreMCP server
Connect NewsletterFIT to Claude, ChatGPT, Cursor or any MCP client. Ask about newsletters, sponsors, companies and topics and get answers grounded in the record.
Learn moreExports
Enterprise JSON exports of recent publications, articles, entities and the links between them, for analysis and research pipelines.
Learn more
Who it's for
Built for people who buy attention, track it, or build on it.
For brands
Find the newsletters your buyers actually read
For agencies
Newsletter media plans your clients can see the research behind
For PR & comms
Know when a newsletter mentions your company
For startups
Your first newsletter sponsorships, without a media team
For data & AI teams
Newsletter data, structured and ready for your pipeline
For sales & GTM teams
Newsletter activity as a buying signal
For investors
What the newsletters are saying about your portfolio and pipeline
For developers & AI agents
Newsletter records in your pipeline or your assistant.
A documented REST API with an OpenAPI 3.1 spec, and an MCP server for Claude, ChatGPT, Cursor and other MCP clients. Every paid plan includes both.
REST
curl "https://newsletterfit.com/api/v1/search?q=ai%20agents" \
-H "Authorization: Bearer nf_live_YOUR_KEY"MCP · CLAUDE CODE
claude mcp add --transport http newsletterfit https://newsletterfit.com/mcp \
--header "Authorization: Bearer nf_live_YOUR_KEY"Free data
Explore the newsletter market, no account needed.
- Newsletter directoryBrowse by topic and audience
- Top SubstacksLargest by public subscribers
- Rising newslettersSustained subscriber growth
- Topics A–ZEvery covered topic
- SponsorsBrands buying newsletter placements
- Sponsorship statisticsMarket-wide figures, updated hourly
Popular topics: AI agents · Cybersecurity · Venture capital · Investing · Product management · Marketing · Personal finance · Economics
How the data works
Every figure says where it came from.
We read public archives, RSS feeds and sitemaps on a rolling schedule. We don't have private publisher metrics such as open rates, so each value says which of these it is.
- Shown publicly
- Subscriber figures the platform or the newsletter's own site displays. Often rounded; a dash when there is none.
- Observed
- Counted from the posts we index: the last post, posts in the last 90 days, publishing cadence.
- Inferred
- Topics and likely audience, classified from recent posts by a language model. Not reader demographics.
- Detected
- Sponsors found from explicit markers such as "Sponsored by", checked against the post text.
Pricing
Start with 7 days of Pro. Keep what you need.
Pro
For researchers, operators and buyers who work in newsletters weekly.
- · 2,000 searches & 10,000 publication profiles a month
- · API & MCP: 500 searches & 2,500 profiles a month
- · Watchlist of up to 500 publications
Intelligence
For teams monitoring a market, competitors or a category.
- · Everything in Pro
- · 10,000 searches & 50,000 profiles a month
- · API & MCP: 2,500 searches & 12,500 profiles a month
Enterprise
For teams that take the graph out of NewsletterFIT.
- · Everything in Intelligence, doubled: 20,000 searches & 100,000 profiles a month
- · API & MCP: 5,000 searches & 25,000 profiles a month
- · Watchlist of up to 5,000 publications, alerts on 500 items
FAQ
Common questions
See the full FAQ for security, integrations, data freshness and billing.
What is NewsletterFIT?
Newsletter data for buyers, researchers and AI agents. We read public newsletter issues across Substack, beehiiv, LinkedIn, Kit, Ghost and custom domains, extract the sponsors, companies, people and topics in each, and make it searchable in the app, over a REST API and through an MCP server.
Who is it for?
Brands and agencies planning newsletter sponsorships, PR and communications teams tracking mentions, sales and GTM teams using newsletter activity as a buying signal, investors following companies and markets, and data and AI teams that want newsletters as a source.
Where does the data come from?
Public newsletter pages, archives, RSS feeds and sitemaps. Subscriber figures are what the platform shows publicly; we don't have private metrics such as open rates. The methodology page explains every label.
Can I use it from Claude, ChatGPT or my own code?
Yes. Every paid plan includes the REST API and the MCP server, which works with Claude, ChatGPT, Cursor and other MCP clients. The docs cover setup, limits and every tool and endpoint.
How does sponsorship intelligence work?
Sponsor placements are detected in each issue we read, so every newsletter shows the brands it has carried and every brand shows the newsletters it has bought. Sponsor names are part of the paid product.
How much does it cost?
Every account starts with 7 days of Pro, no card required. After that, choose Pro, Intelligence or Enterprise to keep using it; annual billing costs less. The pricing page shows current prices.