Anatomi Rupiah

The problem

Bank Indonesia teaches the public a "3D method" for checking banknotes: Dilihat, Diraba, Diterawang (look, touch, hold to the light). Almost everyone can recite the three words. Far fewer can say what a watermark physically is, why intaglio ink feels raised, or what sits inside a security thread. A fourth check, kode tuna netra, the raised marks that let blind people identify a note by touch, is barely taught at all.

There is a legal catch. UU 7/2011 Pasal 24 ayat (1) prohibits imitating the rupiah, up to a year in prison and a Rp200 million fine, unless the reproduction is educational and marked "spesimen." Ayat (2) separately bans distributing imitation notes. I treated both as engineering constraints: teach the mechanism without ever producing anything that could pass for a note.

What I built

I built the legal safeguards before any content

The first real work was legal groundwork and the SPESIMEN marking, before a single note was drawn, since adding legal guarantees after the visuals existed would have been far riskier. The mark is drawn into the shape data of every note diagram, in the same space as the note's outline, so it survives screenshots, printing and any attempt to hide it with styling. The site has no way to produce an unmarked note-like image.

The build fails if a drawing breaks the rules

Nine automated checks run against the rendered output before every build. They confirm there are no photos of banknotes anywhere in the repository, every diagram carries its SPESIMEN mark, every diagram stays smaller than an actual note, and no export can produce a full note. If one fails, nothing ships. I kept the diagrams simple and never photorealistic, because realism itself would defeat the legal exemption.

I drew every mechanism as a diagram

Each security feature has a hand-drawn cross-section: watermark, security thread, intaglio, colour-shifting ink, rectoverso, microtext, UV ink and the tactile code, showing the mechanism better than a photo could. The colour-shift tilt demo, the UV toggle and a raking-light relief for the touch check all compute real light physics live in the browser, with a drawn fallback where they can't run.

Every claim cites Bank Indonesia, and the site never gives a verdict

Every fact about features, denominations, heroes and motifs is structured data that must cite a source, usually a Bank Indonesia publication; the build fails if one is missing. For the newest 2022 series, I re-derived the data from Bank Indonesia's seven implementing regulations. Two of the seven featured figures have no written biography, because the encyclopedia I cite for them doesn't cover those two, and the site names the gap openly. The site explains how to check a feature, never how to make one, and has no camera or "is this real?" button, since that authority belongs to Bank Indonesia.

Photos of people are allowed, photos of money are not

Photos were banned outright at first. I then opened one narrow exception for the heroes on each note and the motifs on the back, since a person or a flower is not currency. The check keeps the two cases apart, so photos of notes are still blocked. Each of the 27 licensed photographs, covering 7 figures and 20 of the 21 described motifs, carries its credit and source.

Result

Anatomi Rupiah is live in Indonesian and English as a static site with no network calls at runtime. It covers 10 denominations: the 2022 series plus the three largest 2016 notes still in circulation. Open any note, click a numbered marker, and see a magnified view beside the mechanism diagram. A guided walkthrough of the 3D method ends by admitting that touch can't be shown on a screen, and sends the reader to handle an actual note. The site names itself a personal educational project under the Pasal 24 ayat (1) exemption, unable to judge whether any note is authentic. The initial build took about two days in August 2026; a second phase, including a dark-theme redesign, continued into September.