Sales.co
sales.co
Done-for-you cold email and AI-assisted lead generation for B2B companies, co-founded with Ryan Doyle.
$90K/mo
Jakob Greenfeld
Physicist turned permissionless entrepreneur, co-founder of Sales.co
@JakobGreenfeld Denmark23K followers$90K/moProductized ServicesCreators & WritersEducators & Course CreatorsMarketing & SEO Tools
About Jakob Greenfeld
Jakob Greenfeld is a German-born entrepreneur and writer based in Denmark who left an academic physics path to run what he calls experiments in permissionless entrepreneurship. Starting in 2020 he shipped a rapid-fire series of small products — data tools, newsletters, podcasts and mini-tools — and documented the whole process publicly on his blog and on X.
Several of those small bets found buyers: Product Explorer, a data product for makers and indie investors, and Gum Spy, which analyzed what sells on Gumroad, were both sold, and the tweet-prompt tool What to Tweet was acquired by Tweet Hunter. He also served as CTO of Alts.co from 2020 through 2021 and ran Opportunities.so, a research-as-a-service newsletter of business ideas for entrepreneurs.
His biggest venture is Sales.co, a cold-email lead generation company he co-founded with Ryan Doyle after the two met on X. Jakob built the lead lists and runs the business day to day as CEO; in a 2024 Indie Hackers interview the company was reported at around $90K a month. He is also the author of the books Unfuck Your Sales and A Skill Called Luck, and is known for spicy, contrarian essays on business ideas, distribution and luck.
Products by Jakob Greenfeld
F
Founder Flywheel
founderflywheel.com
Research-as-a-service newsletter for entrepreneurs.
O
Opportunities.so
opportunities.so
Newsletter of researched business opportunities and ideas for entrepreneurs.
Newsletter Spy
newsletterspy.io
Data on Substack newsletters and what is growing.
Mini-tool serving tweet inspiration prompts; acquired by Tweet Hunter.
Data tool that analyzed what was selling on Gumroad.
Data on indie products for makers and indie investors.
Micro-SaaS surfacing early trend signals for investors, entrepreneurs and marketers.
Revenue
Jakob Greenfeld has publicly reported $90K/mo (Sales.co) (as of 2024). Source
Exit stories
P
Product Explorer
→ Andrew Gazdecki (MicroAcquire) · 2021
Greenfeld felt his data products struggled with churn and had hit a ceiling on recurring revenue, while the buyer had a clear use for it as lead generation for MicroAcquire. He also saw the sale as a chance to learn about acquisitions.
by Jakob Greenfeld
What to Tweet
→ Tweet Hunter · 2021
by Jakob Greenfeld
- Revenue (monthly, log scale)
- First product
- Went full time
- Exit
- Launch / milestone
- Started 2020
- 2020First product: Launched Product Explorer, Gum Spy, Newsletter Spy and What…
- 2020Went full time: Left academia to ship in public
- 2020Milestone: Became CTO of Alts.co, a role he held through 2021
- 2021Exit: Sold Product Explorer, What to Tweet, Gum Spy
- 2021Launch: Launched Opportunities.so, a research-as-a-service newsletter…
- 2022Launch: Launched Founder Flywheel and co-founded the cold email…
- 2024Revenue: Sales.co at ~$90K/month≈ $90K/mo indiehackers.com
Timeline
- 2020 — Left the academic path and started shipping small products in public, beginning with the Bootstrap MBA experiment.
- 2020 — Launched Product Explorer, Gum Spy, Newsletter Spy and What to Tweet in quick succession.
- 2020 — Became CTO of Alts.co, a role he held through 2021.
- 2021 — Sold Product Explorer; What to Tweet was later acquired by Tweet Hunter and Gum Spy was also sold.
- 2021 — Launched Opportunities.so, a research-as-a-service newsletter of business ideas.
- 2022 — Launched Founder Flywheel and co-founded the cold email agency Sales.co with Ryan Doyle.
- 2024 — Sales.co was reported at about $90K per month in an Indie Hackers interview.
How Jakob builds
- Act without asking for permission — most of his wins came from just shipping.
- Launch many small, cheap experiments and let the market tell you which to keep.
- Mine data (marketplaces, newsletters, filings) to find business opportunities others overlook.
- B2B services and distribution often beat building yet another SaaS product.
- The bar is low: most competitors barely try, so consistent effort stands out.
Learn from Jakob Greenfeld
[book]Pay what you want
Unfuck Your Sales
Practical book on cold email and B2B sales from the Sales.co playbook.
[book]
A Skill Called Luck
On increasing your luck surface area as an entrepreneur.
[newsletter]
Jakob Greenfeld's essays
Weekly essays on permissionless entrepreneurship, business ideas and distribution.
[newsletter]
Opportunities
Researched business ideas and opportunities for indie entrepreneurs.
Jakob Greenfeld vs Marko SaricJakob Greenfeld FAQ
Who is Jakob Greenfeld?
Jakob Greenfeld is a German-born, Denmark-based entrepreneur and former physics researcher known for shipping many small products in public and for co-founding the lead generation company Sales.co.
What products has Jakob Greenfeld sold?
He sold Product Explorer and Gum Spy, and his tweet-prompt tool What to Tweet was acquired by Tweet Hunter.
How much does Sales.co make?
In a 2024 Indie Hackers interview, Sales.co was reported at around $90K per month, or over $1M in annual recurring revenue.
What books has Jakob Greenfeld written?
He wrote Unfuck Your Sales, about cold email and B2B sales, and A Skill Called Luck, both sold on Gumroad.
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