Own your stack.
What each one does, how it grows a business, and how to make money with it.
PostHog
OpenSEO
Invoice Ninja
Cal.diy
Autumn
Frappe CRM
Mautic
ChatwootOpen source product analytics you host yourself
39,978 GitHub stars · MIT core
Mixpanel Growth at 20 million events is $2,289 a month if you pay month to month.
That's $27,468 a year.
What people who pay for it complain about
The bill jumps fast once you pass the free tier.
Capterra review, Apr 2026 ↗Tracking anything new usually means waiting on a developer.
Capterra reviews ↗Support can take days to get back to you.
Mixpanel help page: 48-hour reply target ↗

You see the number drop, then click and watch the real person's session, all in the same place. Then flip a feature on for ten percent of users, or run a test, and keep only what works.
Host it yourself and your users, events, and replays stay on your server. You own the code, so Claude Code can change it to fit your business.
Shopify brands doing about $200,000 a year pay you to set up PostHog and show where shoppers quit. About $1,000 setup plus $250 a month.
Find them: Store Leads (from $75 a month) filters Shopify stores by estimated monthly sales; set it to about $15,000–$40,000 a month.
Software companies with 5 to 50 staff pay you a fixed fee to set up PostHog so they can see what users do. $3,000 to $6,000.
Find them: Wappalyzer lists live websites by the analytics tools they run, filterable by country and traffic.
Open source SEO tool you run yourself
21,591 GitHub stars · MIT
Semrush Advanced is $549 a month if you pay month to month.
That's $6,588 a year.
What people who pay for it complain about
Canceling takes a form and an email link, or billing continues.
Semrush help page ↗Pay month to month, and there are no refunds.
Semrush refund policy ↗Constant upsells: extra users, add-ons and higher limits all cost more.
Capterra reviews ↗

The hosted version is $10 a month and includes $10 of data. You see which keywords bring visitors and which pages need fixing.
Self-host OpenSEO for free on Cloudflare's free plan, then plug it into Claude. Your AI pulls keywords, rankings, and audits for you, and you only pay for the searches you run.
Run monthly rank tracking and site audits for small law firms with 2 to 10 lawyers. Charge $1,000 a month; data runs about $10 a client.
Find them: Search Google Maps for "law firm" plus your city and pitch the firms that rank below the top three.
Invoicing and payments app you run yourself
10,126 GitHub stars · Elastic 2.0
FreshBooks Premium is $70 a month if you pay month to month, plus $11 a month for every extra team member.
That's $840 a year, before you add a single teammate.
What people who pay for it complain about
The price keeps going up, with nothing new to show for it.
Trustpilot review, Sep 2026 ↗On the cheapest plan, client number six forces an upgrade.
FreshBooks pricing page ↗Need help? You start with an AI chatbot, not a person.
Trustpilot review, Jul 2026 ↗
Send a quote, turn it into an invoice, get paid by card, and chase the late ones. Add as many clients as you win without hitting a limit.
Sell maintenance plans or retainers? Let Invoice Ninja charge cards automatically and chase late payers. You own the code, so Claude Code can tailor it.
HVAC, pest control, pool and lawn care companies love plans like a "$29 a month tune-up club." You design the plan and set up automatic monthly card billing: new recurring revenue, not software. About $2,500 to set up.
Find them: Google Maps for "HVAC" or "pest control" plus your city. Pick the ones whose websites don't advertise a membership plan yet.
Imagine giving your AI helper a big key ring. One connection lets it use thousands of apps, such as Gmail and Notion, to do everyday chores for you.
zapier.com/mcpIf you write software, this is the same key ring handed to your program instead of your chatbot — a few lines of code and your app can use those thousands of apps too.
zapier.com/sdkNew from Zapier
Describe what you want in Claude or ChatGPT, and your AI builds the Zap and turns it on.
The predictable steps run as plain code, and AI only handles the parts that need judgment.
Zapier's example: a brief before a big call dropped from $1.12 a run to 12 cents.
When a Zap breaks, it can figure out how to recover on its own.
It's in beta now, with a waitlist open.
zapier.com/s/ngz-join-wait-listFree booking pages that sync with your calendar
48,716 GitHub stars · MIT
Calendly Standard is $12 a seat a month if you pay month to month.
For a 10-person office, that's $1,440 a year.
What people who pay for it complain about
Free gets you one meeting type, and everything else costs per seat.
Calendly pricing page ↗Users say it is hard to cancel, and the charges keep coming.
Trustpilot review, Jun 2026 ↗The "Powered by Calendly" badge stays unless you pay.
Capterra review, May 2026 ↗

Put everyone at your firm on one Cal.diy server, each with their own booking page. There are no per-seat fees, so adding a person costs nothing extra.
Losing hours to no-shows? Take a deposit through Stripe when people book. You own the code, so Claude Code can add the reminder emails Cal.diy left out.
One Cal.diy page that says "book a time," paid through Stripe, say $200 for 30 minutes. Ask: What problem can I help you solve? Why me? Why do you think I can solve it? Every paid call shows what your audience trusts you to fix, and will pay for.
Runs your pricing, plans, and billing on Stripe
2,692 GitHub stars · Apache 2.0
Chargebee Flow is $160 a month for a company billing $20,000 a month.
That's $1,920 a year.
What people who pay for it complain about
Prices can double at renewal, once you're locked in.
Trustpilot review, Nov 2025 ↗The fee rises every time your revenue does.
Capterra review, Jan 2026 ↗Support can take days, even weeks, to get back to you.
Trustpilot review, Apr 2026 ↗

If your software has an AI feature that costs you per use, sell credit packs. You own the code, so Claude Code can change the rules.
Put new customers on the higher price while existing ones keep theirs. Move them over when you're ready, not all at once.
Set up plans, trials, and usage pricing for software companies doing $200K to $2M a year, then run their next price increase. About $5,000 a project.
Find them: BuiltWith's list of websites that use a paid billing tool, filtered by estimated revenue.
Chat-style forms and chatbots you host yourself
10,379 GitHub stars · FSL
Typeform Growth Flow is $379 a month if you pay month to month.
That's $4,548 a year.
What people who pay for it complain about
Surprise renewals, and refunds that are hard to get.
Trustpilot review, May 2026 ↗Hit your response cap, and your forms go offline.
Trustpilot review, Aug 2026 ↗Removing the Typeform logo means paying for a bigger plan.
Typeform pricing page ↗
Host it yourself and there is no response cap. Your forms stay online however busy you get.
Selling online? Add a chat that recommends the right product and takes payment. You own it, so Claude Code can change it.
Swap a course seller's plain email form for a short Typebot quiz that sends the best buyers to a sales call. Around $3,000 to set up plus $300 a month.
Find them: BuiltWith's list of websites using Kajabi, filtered by estimated sales revenue.
Open source sales CRM you host yourself
3,618 GitHub stars · AGPL-3.0
Pipedrive Ultimate is $89 per seat a month if you pay month to month.
For a 10-person sales team, that's $10,680 a year.
What people who pay for it complain about
Key features like lead capture cost extra as add-ons.
Capterra reviews ↗Reviewers say cancelling takes a confusing, multi-step process.
Trustpilot review, Aug 2026 ↗Support emails can go unanswered for weeks.
Trustpilot review, Aug 2026 ↗

There is no seat price. Hire another rep and the bill does not move, on a server that can run about $20 a month.
If you run ads, leads drop straight into your pipeline. You own the code, so Claude Code can add your follow-up rules.
Set up Frappe CRM for 3-to-15-person sales teams at agencies, IT shops, and distributors that pay per seat for a CRM. Import their deals and train them for a fixed $3,000 to $6,000.
Find them: Indeed job posts that ask for CRM experience, skipping any company over 50 staff.
Host, back up, and support Frappe CRM for small teams, and make changes on request. About $300 a month per client.
Find them: install the free Wappalyzer browser extension, open the websites of local B2B firms from Google Maps, and it flags the ones running a paid CRM.
Open source email marketing and automation you self-host
10,576 GitHub stars · GPL-3.0
GoHighLevel Agency Pro is $497 a month if you pay month to month.
That's $5,964 a year.
What people who pay for it complain about
Support can take days to answer a ticket.
Trustpilot review, Sep 2026 ↗Texts, emails, and AI are billed on top of the plan.
HighLevel pricing page ↗It is so big that new users take months to learn it.
Roundup of r/gohighlevel threads ↗

Run email sequences on your own server. You pay for the server plus about ten cents per thousand emails, with no plan fee.
Only have a landing page that collects emails? Add Mautic follow-up emails, let Claude Code set them up, and sell to more of your list.
Course and coaching sellers with fast-growing email lists but only a signup page need sequences that turn subscribers into buyers. Set up Mautic for around $2,500 plus $300 a month.
Find them: Kajabi's Hero Stories blog profiles course sellers who passed $100K and $1M in sales.
Open source customer support inbox you self-host
37,292 GitHub stars · MIT core
Intercom Expert is $139 a seat a month if you pay month to month.
For a 10-person team, that's $16,680 a year, before Fin's 99 cents and up for every conversation it resolves.
What people who pay for it complain about
One team's bill was headed from $1,200 to $10,000 a month.
Reddit r/SaaS ↗Fin can charge 99 cents even when your staff had to step in.
Intercom community post, Jan 2025 ↗And a support company's own support can take days to reply.
Trustpilot review, Dec 2022 ↗
Every message from every channel lands in one inbox, so nothing slips. Add support staff freely on the free core if you build or bring your own AI bot, and pay only for the server and your AI usage.
Selling online and answering "where's my order?" all day? Have Claude Code build a bot for Chatwoot's free version, with no per-answer fees.
Set up Chatwoot for 5-to-50-person software companies that pay per seat for support software, for a fixed $3,000 to $5,000.
Find them: Wappalyzer's lists of live websites running a paid support chat widget, starting with the low-traffic sites.