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Research log

Dated record of research dives that shape the platform. Each entry captures the question, what was found, the level of confidence, and what was decided as a result.

This is intentionally append-only. When facts change, add a new entry — don't rewrite old ones. The current-best summary of any topic lives in its own wiki page (e.g. Event-sources); this log is the audit trail behind those pages.

How to use this log

  • One entry per dive. A "dive" is a focused question that produced a decision or a working inventory.
  • Date it. Entries are ordered newest-first.
  • Link out. If the dive produced or updated an inventory page (like Event-sources), link to it. Don't duplicate the table here.
  • Capture caveats. Time-sensitive facts (API gate changes, deprecations) belong in the entry so future readers know when to re-verify.
  • Record the decision. Even "decided to wait" is a decision worth logging.

2026-06-02 — Map & geometry sources for Amsterdam

Question: What cartographic and geometry sources can render the Uitwijken map — base tiles, administrative boundaries (stadsdeel/wijk/buurt), address/building geometry, and street-level detail? This is the map counterpart to the event-pins dive: Open-data named the data types as principles, but the base cartography had never been inventoried at API level.

Method: Three parallel research agents — national PDOK/Kadaster services, Dutch basisregistraties (CBS/BAG/BGT/NWB), and Amsterdam's own municipal geo APIs. Endpoints live-probed against official docs.

Key findings:

  • The map foundation is fully buildable on open data: PDOK (BRT-A base tiles, BAG, BGT, Locatieserver geocoder) + data.amsterdam.nl (gebieden, basiskaart, meldingen), free and no-auth.
  • Use Amsterdam's own gebieden indeling for the platform's scales — it does not map 1:1 to CBS (carries a separate cbsCode field). CBS Wijk- en Buurtkaart is the source for national comparability + statistics.
  • Licensing is mixed: BGT/NWB are CC-0, BRT-A/CBS are CC-BY (attribution needed), Amsterdam basiskaart has bespoke municipal terms.
  • Two distinct BAG APIs: PDOK OGC API (no key, bulk/tiles) vs. Kadaster Individuele Bevragingen (free key, single lookups, rate-limited) — don't conflate.

Decision: Adopt the stack captured in Map-sources. Build the proof-of-concept map foundation on PDOK + data.amsterdam.nl with no commercial cartography dependency. Consider the base-cartography question closed; the civic-overlay layer (permits, plans, budgets) remains open.

Caveats to re-verify:

  • API keys are rolling toward mandatory on both PDOK BAG (Individuele Bevragingen) and data.amsterdam.nl, with no firm deadline — biggest forward-looking risk.
  • Exact BAG/BGT collection identifiers — confirm against live /collections JSON before coding field names.
  • Amsterdam gebieden shows "Licentie: -" while behaving as open/CC-BY — confirm attribution terms.

Open follow-ups: Municipal permits/plans datasets, parkeervakken/bomen and other thematic map layers, BGT vector-tile render budgets at buurt scale, buurtbudget/Stadspas geo channels.

Source pages updated: Map-sources (new), Open-data (cross-link added).

2026-06-02 — Event data sources for Amsterdam

Question: Which sources of geotagged event data exist for Amsterdam and Noord-Holland, and which expose APIs / feeds with title, date, location, and source URL?

Method: Multi-agent deep-research workflow — 6 search angles, 27 sources fetched, 25 claims adversarially verified (24 confirmed, 1 refuted).

Key findings:

  • Gemeente Amsterdam's Datapunt Evenementen dataset is the strongest single source: public, no-auth, CC-BY 4.0, REST + WFS + MVT.
  • Most commercial event APIs (Luma, Meetup, DICE, Eventbrite) are partner-gated, paid, or owner-scoped.
  • Ticketmaster Discovery API v2 is the most accessible commercial source — free key, 5k calls/day.
  • Facebook Events API has been effectively closed since COVID; the canonical community scraper was archived in 2021.
  • Major Amsterdam cultural venues (Melkweg, Paradiso, Pakhuis de Zwijger) publish no API/RSS/iCal — HTML scraping (ideally via embedded Schema.org JSON-LD) is the path.

Decision: Adopt the ingestion priority captured in Event-sources. Ship the "Events this week" map layer on open data + JSON-LD scraping with no commercial dependency. Defer commercial APIs until a business case justifies the cost.

Caveats to re-verify:

  • Datapunt is rolling out a mandatory API key — code should be ready to send it.
  • Meetup tightened its gate in Feb 2025 (Pro tier required for new OAuth consumers); older blog posts are misleading.
  • Venue "no API" claims rest on absence-of-evidence — worth a manual check.

Open follow-ups: Uitagenda / Uit in Nederland, Songkick / Bandsintown / RA paid tiers, civic event channels (Decidim, buurtbudget, Stadspas), Museumnacht / UvA / VU / warenmarkten feeds.

Source pages updated: Event-sources (new), Open-data (cross-link added).

Tags

#year/2026 #city/amsterdam #process/research