Clockwise served 40,000 organizations and is shutting down. Most users will move to Reclaim — and they should. But if you used Clockwise as more than a tool — as a calendar API, across multiple companies, or as the source of truth for billable time — you need something else underneath.
Clockwise was built over almost a decade. Their team is joining Salesforce. Their technology is being deleted.
Reclaim is a fine destination for individuals defending focus time. But for teams whose products, billing systems, or compliance workflows were built on Clockwise — Reclaim is a sidegrade, not an upgrade.
We built OneSlate as the layer underneath those workflows. Multi-org calendar truth, verifiable time, and an API your engineers can actually call.
Most replacements compete on the same axis Clockwise did: making one person's calendar smarter. We're not in that race. OneSlate is the layer that makes calendar a piece of infrastructure — like Stripe is for payments, Twilio is for messaging.
Cronofy is great enterprise infra. Reclaim is great personal AI. Cal.com is great open-source. None of them solve the three problems that Clockwise users actually hit.
If you're a fractional CTO, an investor sitting on five boards, or a founder with three companies — your "real" availability lives across multiple Google Workspaces. Most APIs (including Nylas v3) lock queries inside one organization. We don't.
Pull a signed log of "this person spent X hours with this domain in this week." Use it for invoicing, contractor compliance, or just stop guessing. Domain-resolved, mask-able, audit-grade. The thing your finance team has been asking for since 2019.
Native MCP server. Stable IDs that survive reschedules. Webhooks that don't lie about state. We built OneSlate during the year every meaningful product became agent-callable — and it shows.
If your engineers had to wrestle with Clockwise's GraphQL or Cronofy's Sync engine, you'll find OneSlate refreshingly direct. REST, JSON, idempotent writes, signed reads.
# Multi-org availability — the thing Nylas v3 stopped letting you do curl https://api.oneslate.tech/v1/availability \ -H "Authorization: Bearer $ONESLATE_KEY" \ -d '{ "user_id": "usr_2k9...", "across_accounts": true, "exclude_shared_calendars": true, "window": { "start": "2026-05-05T00:00:00Z", "end": "2026-05-12T00:00:00Z" }, "duration_min": 30 }' # Returns merged free/busy across all connected workspaces. # calendar_kind = primary|owned only — no co-worker noise. { "slots": [ { "start": "2026-05-06T13:00:00Z", "end": "2026-05-06T13:30:00Z" }, { "start": "2026-05-07T09:00:00Z", "end": "2026-05-07T09:30:00Z" } ], "sources": ["jump-inc.co", "mabuchi.tech", "timelab.jp"], "signature": "sha256:9f3a..." }
We don't think OneSlate is the right answer for every Clockwise user. Most individuals should use Reclaim. Most enterprise scheduling teams should evaluate Cronofy. Here's the actual decision matrix.
| Dimension | Reclaim Personal AI | Cronofy Enterprise API | Cal.com Open Source | OneSlate Calendar Infra |
|---|---|---|---|---|
| Replaces Clockwise's UI | Best | No | Partial | No (we're under it) |
| Replaces Clockwise's Calendar Sync API | No | Yes | Self-host needed | Drop-in |
| Multi-org availability (no v3 trap) | No | Yes (expensive) | Self-build | Native |
| Verified time logs for billing | No | No | No | Yes (signed) |
| MCP / agent-native | No | No | No | First-class |
| Entry pricing | $10/seat/mo | $819/mo | $0 (self-host) | $0 (Read tier) |
| Best for | Individuals defending focus time | Large enterprise, regulated | Engineering teams who self-host | Multi-org founders, fintechs, fractional teams |
No "contact sales for a quote." No usage tier you'll accidentally exceed and get a five-figure invoice. Read is free. You pay when we write, you pay more when we verify.
If you used Clockwise as a Calendar Sync API, the migration is mechanical. We've reverse-engineered the contract.
Email + workspace domain. Key emitted instantly. No card. No sales call.
OAuth Google Workspace, Microsoft 365, or both. Cross-org from day one. Same calendars Clockwise managed.
Replace your Clockwise Calendar Sync URLs with api.oneslate.tech/v1/*. The shapes are similar enough that most teams ship same-day.
I built OneSlate because I'm the customer. I'm a director at one company, CMO at another, advisor at a fund, founder of a third. Clockwise was never going to work for me — none of these tools were.
If you're feeling abandoned by the Clockwise sunset, I get it. The good news: you don't need another tool. You need infrastructure. Email me directly if you want to think through whether OneSlate is right for you.
You don't need to commit to anything. Connect a calendar, make a few API calls, see whether the shape of OneSlate fits your stack.
Get your API key →