COMPARISON
ATOMIC BOOKING vs
CAL.COM.
Cal.com is open source and we genuinely like them — Atomic Booking is built on cal.diy, the AGPL community fork. The difference isn't philosophy, it's execution: Cal.com's default cloud hosting is on US infrastructure with Stripe payments. We host in Frankfurt and replaced Stripe with Mollie so you don't have to do it yourself.
Their entry price
$15/user/mo
Teams tier
Our entry price
£5/mo
Photon · €6/mo
Difference
58%
cheaper
EVERYTHING SIDE BY SIDE
WHAT WE HAVE. WHAT THEY HAVE.
| ATOMIC BOOKING Photon · £5/mo | CAL.COM Teams tier | |
|---|---|---|
| CORE | ||
| Monthly entry price (paid tier) | £5 / €6 | $15/user/mo (≈ £11.81) |
| Free tier | Yes — Particle, 1 event type | Yes — generous |
| Lifetime payment option | £129 — Quantum (£99 first 500) | – |
| Unlimited event types on paid tier | ✓ | ✓ |
| Unlimited bookings | ✓ | ✓ |
| Custom branding on booking page | ✓ | ✓ |
| Custom domain (your-brand.com/book) | Add-on £2/mo | – |
| EU/UK SOVEREIGNTY | ||
| Hosting region | Hetzner — Frankfurt + Helsinki | AWS — United States (cloud) |
| Customer data never leaves the EU/UK | ✓ | Self-host required |
| Operating company jurisdiction | United Kingdom | United States |
| GDPR-native (not retrofit) | ✓ | Self-host required |
| Subject to US CLOUD Act / FISA 702 | – | ✓ |
| PAYMENTS | ||
| Subscription billing | GoCardless — SEPA + Bacs DD | Stripe |
| Customer paid bookings | Mollie — EU rails | Stripe + PayPal |
| iDEAL / Bancontact / SEPA support | ✓ | – |
| Wero (EPI European wallet) support | ✓ | – |
| Transaction fee (paid tiers) | 0% (Photon and above) | 2.9% + 30¢ via Stripe |
| Pricing currency | GBP and EUR | USD only |
| SCHEDULING | ||
| Round-robin team scheduling | Electron tier | ✓ |
| Collective availability | Electron tier | ✓ |
| Workflows & automated reminders | Photon and above | ✓ |
| API + webhooks | Photon and above | ✓ |
| Group meeting polls | – | – |
| Calendar overlay UX | Coming Q1 2027 | – |
| INTEGRATIONS | ||
| Google Calendar | ✓ | ✓ |
| Microsoft 365 / Outlook | ✓ | ✓ |
| Zoom / Google Meet / Teams | ✓ | ✓ |
| Salesforce | Coming Q4 2026 | ✓ |
| WhatsApp Business booking flow | Add-on £3/mo | – |
| AI Receptionist (voice bookings) | Add-on £9/mo | Cal.ai |
| TRANSPARENCY | ||
| Open source code | AGPL — public on GitHub | AGPL — upstream |
| No-show insurance | Add-on £1/booking | – |
| Calendly migration tool | Free first 60 days | ✓ |
| Charity / non-profit discount | 50% off Photon and Electron | – |
| Student / educator discount | Photon free with .ac.uk / .edu | – |
THE STRUCTURAL ARGUMENT
WHY THE PRICE DIFFERENCE EXISTS.
Cal.com's pricing reflects their cloud infrastructure costs (AWS) and Stripe processing on every paid booking. We use the same open-source foundation but a different stack: Hetzner instead of AWS, Mollie instead of Stripe, GoCardless for direct debit. The price difference comes from substitutions, not from cutting features.
| Payment method | Fee on £100 | Net to merchant |
|---|---|---|
| Stripe (most US schedulers) | £3.10 | £96.90 |
| Mollie iDEAL / Bancontact | £0.29 | £99.71 |
| Wero (via Mollie) | £0.25–0.40 | £99.65+ |
| SEPA Direct Debit (GoCardless) | 1% capped at £4 | £99.00 |
That ~3% gap on every paid booking is the structural saving we pass on. Software margin doesn't depend on cutting features — it depends on cutting card-processor rent.
HONEST TAKE
When Cal.com is the better choice.
We're not the right answer for everyone. Cal.com is the better choice if:
- →You want to self-host on your own infrastructure
- →You've already built workflows on Cal.com's platform API
- →You need their Organizations tier features today (SCIM, advanced SSO)
- →You prefer the upstream version with the original team's support
For everyone else — solo professionals, EU/UK teams, agencies, and anyone who's quietly uncomfortable with American SaaS — keep reading.
COMING Q3 2026
Get early access.
Drop your email — we'll let you know the day Photon goes live, and you'll get founder pricing on Quantum (£99 vs £129 lifetime).
We'll email you when Photon goes live. We don't spam, sell your address, or use trackers. Your email is stored on a Hetzner server in Frankfurt and you can ask us to delete it any time.
OTHER COMPARISONS