7 Open Source Tools That Replace Expensive SaaS (I Use These Daily)

SaaS subscriptions add up fast. A CRM here, a project manager there, an email tool, an analytics suite — suddenly you are paying €500+/month just to run a small business.

Here are 7 open source alternatives I actually use. They are free, self-hostable (if you want), and genuinely good.

1. Notion Alternative → AppFlowy

What it replaces: Notion ($16/month)

AppFlowy is an open-source Notion alternative built with Flutter and Rust. It works offline, stores data locally by default, and has no vendor lock-in.

Best for: developers, privacy-conscious users, people who hate subscription creep.

Setup: download from appflowy.io — 5 minutes.

2. Google Analytics Alternative → Plausible / Umami

What it replaces: Google Analytics (free but invasive), premium analytics ($50-200/month)

Umami is a clean, privacy-focused analytics tool you can self-host on a free Vercel/Railway instance.

Features: page views, unique visitors, referrers, countries — all without cookies.

Setup: deploy to Vercel for free in 10 minutes. No cookies banner needed.

3. Calendly Alternative → Cal.com

What it replaces: Calendly Pro ($12/month)

Cal.com is open source, feature-complete, and free to self-host. It supports team bookings, workflows, and custom domains.

Setup: cloud.cal.com (free tier) or self-hosted on Railway.

4. Mailchimp Alternative → Listmonk

What it replaces: Mailchimp ($13-350/month depending on list size)

Listmonk is a self-hosted newsletter tool. You pay only for email delivery (SendGrid free tier = 100 emails/day).

For a 1,000-person list: €0/month instead of €30+.

Setup: Railway deploy in 15 minutes, point to your SendGrid account.

5. Slack Alternative → Mattermost

What it replaces: Slack Pro ($7.25/user/month)

Mattermost is the open-source team chat. Self-hostable, works on every platform, and integrates with GitHub, Jira, Jenkins.

For a team of 5: saves €435/year.

6. Airtable Alternative → NocoDB

What it replaces: Airtable Plus ($10/user/month)

NocoDB turns any SQL database into a spreadsheet interface. It connects to MySQL, PostgreSQL, SQLite, and more.

Setup: one Docker command or Railway deployment.

7. Zapier Alternative → n8n

What it replaces: Zapier ($20-50/month)

n8n is a workflow automation tool with 200+ integrations. Self-host for free, or use their cloud at €20/month.

For basic automations: Railway free tier handles it.

The Cost Comparison

SaaS Stack	€/month	Open Source Alternative	€/month
Notion	€16	AppFlowy	€0
Analytics	€50	Umami	€0
Calendly	€12	Cal.com	€0
Mailchimp (1K)	€30	Listmonk	€0
Slack (5 users)	€36	Mattermost	€0
Airtable (2 users)	€20	NocoDB	€0
Zapier	€20	n8n	€0
Total	€184	Total	€0

Annual savings: €2,208

The Trade-offs

Open source is not always better:

• You manage updates and backups
• Setup takes more time upfront
• Some features lag behind the paid versions
• No customer support (community forums instead)

For solo founders and small teams who are comfortable with basic tech: the savings are real.

My Setup

For client work and content creation, I use a mix — some SaaS where time > money, open source where the setup is simple.

For client and project tracking, I use a custom Notion setup (still the best for knowledge management IMO). I built a full system that handles CRM, invoices, projects, and finance in one place.

If you want that system without building it from scratch: Freelancer OS on Gumroad — €19.

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What open source tools do you use? Drop your stack in the comments.

More tools and resources: guittet.gumroad.com