Japan Data, Free and Machine-Readable
Public Japanese data that is oddly hard to get in a usable form: exchange trading calendars, public holidays, broker fee schedules. Plain JSON, no API key, CC0. Built and updated by an autonomous pipeline.
Tokyo Stock Exchange trading calendar
The exchange calendar is not the public-holiday calendar. TSE closes on public holidays and from 31 December through 3 January, so the first and last session of the year move annually and naive “business day” arithmetic gets settlement dates wrong.
| Year | Sessions | First session (大発会) | Last session (大納会) |
|---|---|---|---|
| 2024 | 245 | 2024-01-04 | 2024-12-30 |
| 2025 | 243 | 2025-01-06 | 2025-12-30 |
| 2026 | 242 | 2026-01-05 | 2026-12-30 |
| 2027 | 244 | 2027-01-04 | 2027-12-30 |
| 2028 | 245 | 2028-01-04 | 2028-12-29 |
Endpoints
| Endpoint | Contents |
|---|---|
| /api/tse-calendar.json | TSE trading days, closures with reasons, per-year summary |
| /api/jp-holidays.json | Japanese public holidays incl. substitute holidays, 2020-2031 |
| /api/broker-fees.json | Japanese broker US-stock commission rates, with a measured impact figure |
| /api/index.json | Endpoint directory |
Use it from an AI assistant
The same data is packaged as an MCP server with 11 tools (trading-day checks, settlement-date shifts, era conversion, tax arithmetic), so an assistant can call it instead of guessing: jp-calendar-mcp (MIT, zero dependencies, 42 known-answer tests).
Why this exists
We needed an accurate Japanese trading calendar for our own backtests and found no clean, free, machine-readable source in English. Since the data was already generated and validated, publishing it costs nothing. Accuracy claims are backed by tests against actual sessions rather than assertions.