Astrocal is the closest competitor to AvailEngine — both are API-first booking platforms with REST APIs, webhooks, and AI tooling. But they differ in architecture philosophy, pricing, and API design. Here's an honest, side-by-side breakdown to help you decide.
📖 Try AvailEngine →Both AvailEngine and Astrocal are modern, API-first booking platforms. Here's what they share:
| Feature | AvailEngine | Astrocal |
|---|---|---|
| REST Booking API | ✓ | ✓ |
| Webhooks | ✓ Full lifecycle | ✓ |
| Google Calendar sync | ✓ Two-way | ✓ Two-way |
| Stripe deposits | ✓ Native | ✓ |
| AI / MCP support | ✓ Claude Code, Cursor | ✓ |
| Programmatic event creation | ✓ POST /events | ✓ |
| Free tier available | €0/mo | $0/mo |
The key differences that matter when choosing an API-first booking platform.
✗ Astrocal lacks granular API key permissions
Astrocal API keys are all-or-nothing. You cannot create keys scoped to specific operations (read-only, write, admin) or tied to specific tenants. This limits safe delegation in multi-developer or multi-tenant scenarios.
✓ AvailEngine: Granular scoped API keys
Every API key can be scoped by permission level and tenant. Generate read-only keys for monitoring, write keys for integration, and admin keys for configuration. Revoke or rotate any key independently without affecting others.
✗ Astrocal does not support idempotent requests
Retrying a failed booking creation in Astrocal risks double-booking. There is no Idempotency-Key mechanism to safely retry requests. Clients must implement their own deduplication logic.
✓ AvailEngine: Idempotency-Key support built in
Pass an Idempotency-Key header on any POST/PATCH request. If the request succeeds but the response is lost, retry with the same key — the API guarantees the same result without side effects. No double bookings, no double charges.
✗ Astrocal requires self-hosted setup for multi-tenant
Astrocal's cloud offering is single-tenant oriented. Running a multi-tenant platform typically requires the self-hosting option, adding infrastructure management overhead.
✓ AvailEngine: Native multi-tenant in the cloud
Every Scale plan includes native multi-tenant support. Isolated data, independent API keys, separate webhook configuration per tenant — all managed through the AvailEngine API and dashboard, no self-hosting required.
✗ Astrocal is USD-priced, starts at $199/mo for API access
Astrocal's pricing: Free ($0, limited) → Hobby ($19/mo) → Pro ($99/mo) → Business ($199/mo for full API access). Full API features with multi-tenant and advanced webhooks require the Business tier at $199/mo.
✓ AvailEngine: EUR-priced, full API from €0/mo, Scale at €129/mo
All API features are available on the Free tier (100 events/mo). Full multi-tenant and advanced features unlock at €129/mo — saving €70/mo vs Astrocal's comparable tier. European pricing in EUR means no FX surprises for EU businesses.
✗ Astrocal API has a steeper learning curve
Astrocal's API uses resource-oriented design but introduces custom concepts (e.g., "scheduling links" vs plain event types) that mirror their app's data model. Documentation assumes familiarity with the Astrocal app.
✓ AvailEngine: Designed for API-first developers
AvailEngine's API follows REST conventions that feel familiar to any developer: events, bookings, availability, webhooks. curl examples on every endpoint. MCP server for Claude Code and Cursor. From API key to first booking in under 5 minutes.
What you get at each tier, side by side.
Free tier — full API
Scale plan
Free tier — limited API
Business plan (full API)
AvailEngine's Scale plan at €129/mo saves €70+/mo vs Astrocal's comparable Business tier at $199/mo, with native multi-tenant and idempotency included.
Full side-by-side of all capabilities.
| Feature | AvailEngine | Astrocal |
|---|---|---|
| Scoped API keys | ✓ Granular | ✗ |
| Idempotency-Key support | ✓ | ✗ |
| Multi-tenant (cloud) | ✓ Native | Self-host only |
| Stripe deposits via API | ✓ Native | ✓ |
| Webhooks with retries | ✓ Full lifecycle | ✓ |
| Google Calendar two-way sync | ✓ | ✓ |
| MCP / AI editor support | ✓ | ✓ |
| EUR pricing (no FX fees) | ✓ | USD only |
| Full API on free tier | ✓ | Limited |
| Paid tier (full API) starts at | €129/mo | $199/mo |
| Self-hosting available | On request | ✓ |
| EU hosted / GDPR | ✓ | US-hosted |
Choose AvailEngine if you need scoped API keys for secure delegation, idempotency for safe retries, native multi-tenant in the cloud, EUR pricing without FX surprises, or a more affordable full-API tier (€129 vs $199). Choose Astrocal if you need self-hosting as a core requirement, prefer US-based hosting, or have existing investment in the Astrocal ecosystem.
📖 Get Started with AvailEngine →