Calnode vs. calrs vs. Tymeslot: three self-hosted answers to Calendly

Calnode launched as an Apache-2.0 self-hosted Calendly alternative distributed as a single Go 1.26 static binary with an embedded SQLite database, requiring no Redis, Postgres, or separate API server. Calnode ships a REST API with 88 endpoints, HMAC-signed webhooks configurable via API, a native MCP server built on the official Go SDK with stdio and Streamable HTTP transports, and optional first-party LiveKit video rooms with recording and an AI notetaker exposed as MCP tools and webhooks. The project positions itself against cal.com, which it says spans 500k+ lines of TypeScript across roughly 100 packages and needs a 4 GB+ image with Redis, Postgres, and an API server, while Calnode runs from a single docker run command on a $5 VPS.

A lean, self-hostable scheduling engine that lives in your AI stack. Calnode is a Calendly-style booking app — with first-party video meetings, recording, and AI notetaking built in — shipped as a single Go binary with an embedded SQLite database: no Redis, no Postgres, no separate API server, no multi-gigabyte image. It's API-first, webhook-native, and built for a world where agents do the booking. Self-host the whole thing on a $5 box; nothing is paywalled. Calnode runs for pennies on a small VPS — it's a single static binary serving a SQLite file, so there's almost nothing to pay for. Apache-2.0 · Go 1.26 · single static binary · SQLite + Litestream Kick the tires — one command, no config: docker run -p 3000:3000 -v ./data:/data ghcr.io/calnode/calnode:latest → open http://localhost:3000 The whole app — booking pages, admin UI, SQLite — in one container, with data in ./data . With no encryption key set it runs on an ephemeral one fine for a look; stored credentials won't survive a restart . Deploying for real — HTTPS, a persistent encryption key, backups — see Deploy for real deploy-for-real below, or the full DEPLOY.md https://github.com/Calnode/calnode/blob/main/DEPLOY.md . - One binary, one file. Pure-Go SQLite no CGO compiles to a fully static binary. docker run it, or drop it on a VPS. No external services to orchestrate built-in video, if you turn it on, is the one add-on — it needs a LiveKit server . - Meetings built in. Optional first-party video rooms LiveKit as a booking location — guests join in-browser, no app or account. Recording lands in your own Litestream backup bucket no extra storage to provision ; an AI notetaker turns each call into a transcript + notes, exposed as MCP tools and webhooks. The one add-on: video needs a LiveKit endpoint Cloud or self-hosted . - API-first, agent-ready. A full REST API 88 endpoints with API keys and HMAC-signed webhooks configured via API — script every booking action from Claude, ChatGPT, n8n, or curl. Plus a native MCP server built into the binary official Go SDK; stdio + Streamable HTTP so agents get first-class booking tools. - Modern, no bloat. Go backend + a SvelteKit 5 admin app; public booking pages are server-rendered Go templates for instant first paint and a tiny payload. - Correct by construction. DST-safe time handling UTC instant + IANA name , a transactional double-booking guard, and native-API calendar free/busy never stale .ics feeds . - Yours. Instance-per-tenant by design — one deployment is one isolated workspace, your data, your calendar credentials. No shared multi-tenant database. - Easy to extend. A clean Go codebase with sqlc -generated queries — not a 100-package monorepo. Add an endpoint without spelunking. The default open-source scheduler is a SaaS monolith. Calnode is the opposite. | | cal.com | Calnode | |---|---|---| | Codebase | 500k+ LOC TS across ~100 packages | Lean Go + one SvelteKit app | | Runtime deps | 4 GB+ image; needs Redis + Postgres + API server | One static binary + a SQLite file | | Database | Postgres + Redis | SQLite WAL + Litestream point-in-time backup | | Webhooks | UI-only | API-first , HMAC-signed, per-webhook payloads | | AI / agents | None | REST API + webhooks + a native MCP server stdio + HTTP | | Video & recording | Third-party links Zoom / Meet | Built-in in-browser rooms + recording + AI notes self-hosted LiveKit | | Deploy | Orchestrate several services | docker run one container | | Isolation | Shared multi-tenant DB org id everywhere | Instance-per-tenant — isolation is the default | | Licence | AGPL-3.0 | Apache-2.0 , nothing paywalled for self-host | cal.com figures reflect its public footprint; see the the design docs for the full rationale. If you're weighing self-hosted schedulers and you want small, fast, scriptable, and AI-ready over feature-maximal, Calnode is built for you. Everything a human can do, an agent can do — over the API today: Find slots and book, with an API key curl -s "$BASE/v1/event-types/intro-call/slots?from=2026-06-16&to=2026-06-20&tz=Pacific/Auckland" \ -H "Authorization: Bearer $API KEY" curl -s -X POST "$BASE/v1/bookings" -H "Authorization: Bearer $API KEY" \ -H 'Idempotency-Key: 9f3c…' -H 'Content-Type: application/json' \ -d '{"event type slug":"intro-call","start at":"2026-06-17T21:00:00Z","name":"Alex","email":"alex@example.com","timezone":"Pacific/Auckland"}' Wire booking lifecycle events booking.created / .rescheduled / .cancelled to n8n / Make / your own service with HMAC-signed webhooks — all configured through the API, not buried in a UI. Native MCP server. A Model Context Protocol server is compiled into the binary official Go SDK , exposing eight first-class tools — list event types , get event type , get available slots , create booking , get booking , reschedule booking , cancel booking , list bookings . The MCP tools call the same internal services as the REST API no parallel code path , so booking side effects — calendar events, confirmation emails, webhooks, reminders — fire identically. Two transports: - stdio for local agents — run calnode mcp logs to stderr, JSON-RPC on stdout . - Streamable HTTP at POST /mcp for remote agents. Calnode is its own OAuth 2.1 authorization server dynamic client registration + PKCE , so an agent adds the server by URL and clicks Connect → signs in with the workspace's Google/Microsoft login → approves a consent screen — no pre-shared key. A cno API key also works Authorization: Bearer <key for scripts. The Connect UX needs HTTPS — it shines on a deployed instance. User: "Book a 30-min call with Wynne next week — I'm in Auckland." Agent: get available slots "intro-call", "2026-06-16", "2026-06-20", "Pacific/Auckland" → presents options → create booking … → returns confirmation + meeting link Conversational booking — in the booking page itself. Beyond agents, the booking page and the embed widget ships an optional "Book by chat" assistant: a visitor types "free Tuesday afternoon or next week" and it resolves real availability and books — the deterministic engine still computes the slots the model never invents times , and the assistant only ever sees free/busy windows, never your calendar contents. Bring your own model — any OpenAI-compatible endpoint a hosted model or one you run yourself ; off by default, with the standard calendar always there as the fallback. Connecting Claude remote / HTTP . In Claude claude.ai or Desktop → Settings → Connectors → Add custom connector → enter https://<your-instance /mcp → Connect → sign in → Allow . Custom connectors need a paid Claude plan; the server must be on HTTPS. Local stdio alternative any plan : point an MCP client at the calnode mcp subcommand via its config file — no OAuth, runs against the local DB. Permissions. MCP tools are role-scoped , mirroring the rest of the app: an owner/admin acts across the whole workspace, a member sees and manages only bookings they host. The stdio subcommand is the local operator → full access. Booking creation and availability are the public booking surface, open to all. Roles are fixed owner / admin / member ; configurable RBAC is intentionally out of the lean core. docker run -d -p 3000:3000 \ -e BASE URL=https://booking.example.com \ -e CALNODE ENCRYPTION KEY="$ openssl rand -hex 32 " \ -e CALNODE RECOVERY SECRET="$ openssl rand -hex 32 " \ -e DATABASE URL=sqlite:///data/calnode.db \ -v calnode-data:/data \ ghcr.io/calnode/calnode:latest Pinning a version. :latest follows the newest tagged release; :edge tracks main . For reproducible deploys, pin a release — :0.1 tracks patches within the minor or an exact :0.1.0 . See releases https://github.com/Calnode/calnode/releases . Open / → it redirects to /admin/ and walks you through first-run setup create the owner account, connect a calendar, add an event type . Put a TLS-terminating proxy in front that forwards the original Host header. Full guide → DEPLOY.md https://github.com/Calnode/calnode/blob/main/DEPLOY.md env vars, Railway step-by-step, custom domains, Resend email, Google & Microsoft OAuth, Litestream backups, troubleshooting . Shipped - Event types with per-type duration, location, custom questions, custom email copy - DST-correct availability working hours, day-of-week rules, date overrides - Team routing: fixed · round-robin · collective · priority - Google Calendar & Microsoft 365 / Outlook — native free/busy conflict checks behind one provider abstraction; auto Google Meet / Teams links, minted only when the host's connected calendar matches the platform else a manual link is used - Sign in with Google or Microsoft OAuth , email + password, or passwordless magic-link - CalDAV calendars — iCloud / Fastmail / Nextcloud via app-password free/busy + event write-back - Public booking + self-serve reschedule/cancel via signed manage links - HTML branded email logo, banner, business name, size/opacity with add-to-calendar links - REST API 88 endpoints + API keys; HMAC webhooks with per-webhook payloads + delivery log - Native MCP server 10 tools incl. meeting notes + transcript; stdio via calnode mcp + Streamable HTTP at /mcp - Conversational booking "Book by chat" on the booking page + embed widget; BYO-LLM, off by default - Paid bookings — Stripe Checkout pay-then-book: the slot is held, confirmed on the payment webhook, auto-refunded on cancel - Zoom — per-host OAuth; a Zoom-located booking mints a meeting under the assigned host's account - Built-in video meetings LiveKit — in-browser rooms as a booking location no app or account for guests ; host controls end-for-all, hand-off and reclaim host, attendee screen-share toggle , meeting recording straight to your own Litestream backup bucket the same one you already use for DB backup — no extra storage to provision with in-app downloads, recording consent notice + consent-or-leave , and an AI notetaker Deepgram transcript → LLM notes . Headless-consumable: MCP get meeting notes / get transcript + recording.completed / transcript.ready / notes.ready webhooks. BYO LiveKit endpoint Cloud or self-hosted ; configured in Settings → Video — see docs/VIDEO.md https://github.com/Calnode/calnode/blob/main/docs/VIDEO.md - 9 languages on every booker-facing surface - booking page, manage/reschedule page, embed widget, all four emails, and the calendar invite: English · Spanish · French · Canadian French · German · Italian · Portuguese · Dutch · Swedish . Picked from Accept-Language with a footer switcher and an operator-set fallback language; the booker's choice is stored on the booking, so reminders arrive in the language they booked in. Adding a language is adding one JSON file - no code change. The admin UI and the built-in video room are English-only. Non-English translations are machine drafts without native review - corrections by PR are very welcome. - Embeddable booking widget Shadow-DOM web component; inline + popup - Members, roles owner/admin/member , email-token invitations - Idempotency-Key on booking creation; transactional double-booking guard - Envelope encryption at rest secrets sealed with a KEK; recovery escrow - Optional analytics: <head code injection + window.dataLayer events GTM/GA4 On the roadmap - OpenAPI spec · /metrics · multi-domain one instance, many hostnames - Backend: Go 1.26 · pure-Go SQLite modernc.org/sqlite , CGO-free → static binary · goose migrations - Admin UI: SvelteKit 2 / Svelte 5 · Vite 8 · Tailwind 4 · shadcn-svelte embedded at compile time via go:embed - Public pages: server-rendered Go html/template + vanilla JS no framework runtime - Durability: SQLite WAL + optional Litestream replication S3/R2 for backup & point-in-time restore - Background work: in-process job queue on the same DB — reminders, webhook delivery, calendar reconciliation. No broker. A few load-bearing decisions full detail in the the design docs : - The DB is the source of truth; external calendars are a projection. A booking exists once it's committed locally; syncing to Google is a retryable side effect. - Time = UTC instant + IANA timezone name , never a fixed offset — availability resolves to UTC per-date so DST shifts never corrupt a slot. - Single process, no external services. Durability comes from Litestream, not a second datastore. The one exception is optional built-in video: it talks to a LiveKit server — Cloud or self-hosted — only when you enable video. - Instance-per-tenant. Each install is one workspace; isolation is a feature, and the self-host and cloud codepaths are identical. Calnode's backend is small enough to fit entirely in one LLM's context window — most scheduling software cal.com included can't say that. AUDIT.md https://github.com/Calnode/calnode/blob/main/AUDIT.md turns that into a self-serve check: a copy-paste scanner block govulncheck, gosec, gitleaks across full history, SBOM, semgrep — all neutral, standard tooling you run yourself , an adversarial LLM prompt-pack for your own coding agent, and a claims → verification manifest https://github.com/Calnode/calnode/blob/main/audit/claims.yaml mapping every security claim we make to exactly how to check it in the source. Not a certification — a due-diligence accelerator. Self-hosting is free forever — docker run it and you own the whole thing. If you'd rather not run it yourself, Orchestratr https://calnode.com/services — the team behind Calnode — will deploy and operate it for you: - Production deployment on your infrastructure — VPC, private cloud, or bare metal - SSO SAML / OIDC integrated with Okta, Entra ID, or Google Workspace - Calendar, Zoom & CRM integration wired into your existing stack - Migration off Calendly / cal.com, plus bulk user & team provisioning - Training & ongoing support for your ops and IT teams Built for regulated and mid-to-large orgs that need Calnode on their own infrastructure, fully integrated. → calnode.com/services https://calnode.com/services Apache-2.0 https://github.com/Calnode/calnode/blob/main/LICENSE . The full scheduler is self-hostable, and nothing previously free is ever paywalled. The code is Apache-2.0; the "Calnode" name and logo are not — see TRADEMARK.md https://github.com/Calnode/calnode/blob/main/TRADEMARK.md use the code freely; name your fork something else . Contributions are accepted under a CLA https://github.com/Calnode/calnode/blob/main/CLA.md so the project can stand behind every line and keep its future licensing options open — see CONTRIBUTING.md https://github.com/Calnode/calnode/blob/main/CONTRIBUTING.md .