HOLOMARK
Price it. Stack it. Flip it.
One Piece Card Game prices, sets and sealed products, updated daily from TCGplayer.
Search any card or sealed product, see what a buyer should offer, track price history,
keep a wishlist, and run a portfolio of what you own.
- Buyer pays = 80% to 90% of TCGplayer's lowest listing. The market price (recent sales) is shown for reference.
- Prices reflect all conditions, not just Near Mint.
- Prices are in US dollars, with a currency picker that converts using the day's exchange rates.
What's in the app
| Page | What it does |
|---|
| Home | Landing page: the slogan, what the site does, two ways in (Products and Portfolio) and three headline numbers. Search is the button in the top bar |
| Products | Grid or list, sort, filters (set, language, product type, rarity, price). Everything stays in the address bar |
Product (/product?id=...) | One page for every card and sealed product: prices, price history chart, other printings, wishlist, add to portfolio |
| Sets and set pages | Every release, newest first, with scoped search and set analytics |
| Wishlist | Saved on this device, one entry per product variant |
| Portfolio | Holdings with quantities and what you paid, total value, daily change, gain or loss, a value graph, breakdown, most valuable, market trends, backup and restore |
Wishlist and portfolio are saved in the browser until accounts exist (Google sign-in is the next step).
Where the data comes from
tcgcsv.com is a free daily copy of TCGplayer's catalog and prices
(One Piece is category 68). It updates once a day, around 20:00 UTC. We never scrape tcgplayer.com.
Limits worth knowing:
- English only, mostly. The category is the English game. It also lists a few Japanese-version items (the anniversary sets), which HOLOMARK labels as Japanese. Full Japanese card prices need another source.
- No sales data. tcgcsv gives prices, not individual sales, so there is no sales volume and HOLOMARK doesn't estimate any.
- History starts on Oct 20, 2026. tcgcsv withdrew its price archive, so earlier days can't be rebuilt. Charts fill in one point per day.
How it works
- A GitHub job (
.github/workflows/nightly-update.yml) runs every day at 21:30 UTC. It runs update_prices.py, which downloads everything and saves:
data/catalog.json: every product with today's pricesdata/history/<date>.json: that day's prices, kept foreverdata/sets.json: every set with its release datedata/rates.json: exchange rates
- It checks the download is complete, commits those files, and Vercel rebuilds the site from the commit. Vercel never downloads prices itself.
- The site is a static Next.js export (
next build writes out/). Pages read the saved files at build time:
/data/index.json: the catalog the browser downloads once and searches locally/data/h/00.json ... 63.json: price history in 64 small files, so a page loads only the slice it needs
- Everything else (search, filters, wishlist, portfolio) runs in the browser.
Working on it
npm install
npm run dev # http://localhost:3000
npm test # portfolio maths (Node's built-in test runner)
npx tsc --noEmit # type check
npm run build # writes out/
Pushing to any branch runs the Check workflow (Python checks, tests, type check, build).
You can run Nightly price update by hand from the Actions tab on any branch.
Files
update_prices.py: downloads prices; names sealed product types and languageslib/portfolio.ts + lib/portfolio.test.ts: portfolio maths, testedlib/data.ts: build-time data layer (computed once per build)lib/brand.ts: the site's name, in one place. Saved data keeps the old vendr. key prefix in the browser on purpose, so a rename never empties anyone's wishlist or portfoliocomponents/logo.tsx: the logo, drawn as vector paths (Outfit Bold letters, with the M as a rising price line). It is artwork, so a rename means redrawing it. app/icon.svg is the matching tab iconcomponents/, app/: the pagesapp/globals.css, app/portfolio.css: the design system (tokens at the top: colours, the one accent, corner radius, glass)components/flow.tsx: the arch of light behind the whole site, drawn with WebGL. It barely moves, takes its colours from the tokens, stops for reduced motion, and falls back to a still glow where WebGL isn't available
Changing the buyer percentages
Edit BUYER_MIN_PERCENT and BUYER_MAX_PERCENT in lib/data.ts, then push.
If a name shows up as a printing
Some parentheses in TCGplayer names are part of a character's name, like Mr.3 (Galdino).
These are listed in NAME_LABELS in update_prices.py. Add new ones there.
