From zero to your first ROI.
In 5 minutes flat.
Account creation, adding your first item, reading prices, manual refresh, alerts — this guide covers everything.
Create your account
Cault is free to sign up — no credit card required. Simply enter your email and choose a password.
Password
Check your inbox to confirm your address, then sign in.
Create your first collection
After signing in, create your first collection. Give it a name (e.g. "My LEGO collection", "My Pokémon cards") and choose the type. LEGO is available now — more universes are coming.
Collection name
Type
Pokémon TCG is coming soon. Magic, Hot Wheels and more will follow.
Add your first item
In your collection, click Add an item. Search by set number (e.g. 75192) or by name. The BrickLink catalogue is integrated — find your item in a second. On mobile, the barcode icon scans LEGO boxes directly.
Millennium Falcon
75192 · Star Wars · 7 541 pieces
Purchase price
E.g. €800
Condition
Sealed / New / Used
Purchase date
Optional
Quantity
1 by default
The purchase price is the only required field to calculate your ROI. On mobile: scan the EAN barcode on the box directly.
Understand your 3 prices
As soon as you add an item, Cault automatically fetches two external prices and combines them with your purchase price to calculate your ROI.
Your purchase
What you paid
Retail Brickset
Official LEGO.com price (DE/US)
Marché BrickLink
Secondary market price — sealed
Your ROI
vs your purchase price
Refresh your prices
BrickLink and Brickset prices are cached for 48h. Cault updates them automatically in the background. But you can force a refresh at any time.
Millennium Falcon · 75192
Last updated: 2h ago
Update frequency
Automatic — every 48h for each item in your collection
On demand — Refresh button on any item
On add — prices fetched immediately when adding an item
Create a price alert
Three alert types are available. The sell target is the most powerful: when your target price is reached, Cault notifies you with direct access to the sell form.
New alert — 75192 Millennium Falcon
Type
Sell target
Target price
1 800 €
Current price
1 502 €
Progress
83 %
Alerts also work on your wishlist — ideal for monitoring an item before purchasing.
Feature available on paid plans — coming soon.
Tips
Get the most out of Cault.
Enter the exact purchase price
It's the only field Cault can't guess. The more accurate it is, the more reliable your ROI. An estimate is better than nothing.
Condition changes everything
A sealed LEGO set is worth 2 to 3x more than a built one. Choose "Sealed" if the box is intact — BrickLink returns condition-specific prices.
Automatic refresh
You don't need to do anything: Cault updates your prices every 48h. On a specific item, the Refresh button forces an immediate update from BrickLink.
Alerts on wishlist too
Add an item to watch in your wishlist and create a buy alert. Cault notifies you when the price drops — ideal for anticipating retirements.
Retail vs market: two logics
The Brickset retail price shows the official LEGO.com value. The BrickLink market reflects real transactions. ROI is calculated on the market price.
Multiple collections
Create a collection per theme or storage location. The dashboard shows the overall ROI of all your collections combined.
Multiple copies of the same set
Enable "Merge duplicates" in the collection view to group identical copies. When selling, Cault asks which one — sealed or disassembled — you want to sell.
Anticipate retirements
The "Upcoming retirements" page lists all sets leaving production in the next 6 months. This is the optimal buying window for a LEGO investment — prices rise after retirement.
Keep a tax record
If you sell regularly, use the tax export from the Transactions page. It generates a CSV of all your disposals by year, ready for your accountant or tax return.
Visual guide
Reading and understanding each block.
Every number displayed in Cault has a precise meaning. Here is how to read them, with concrete examples.
Dashboard
The Collection Value block
The first block you see on the dashboard summarises the financial state of your entire collection.
Estimated total collection value
12 450 €
↗ +3,1% this month▲ This year : +1 200 €
ROI
▲ +13,0%
incl. +€150 gifts ⓘ
Sets
8 450 €
+8,2%
Minifigs
4 000 €
+24,1%
12 450 € — Sum of the current BrickLink market prices of all your items (new or used depending on each one's condition).
↗ +3,1% this month — Change in value since the 1st of the current month, based on automatic snapshots. Reflects only price movements, not your purchases.
▲ +1 200 € this year — Difference in euros between today's value and the value exactly 1 year ago (historical snapshot).
ROI +13,0% — Weighted portfolio return. Formula: (market value − total invested) ÷ total invested × 100. Items at €0 (gifts) are excluded.
incl. +€150 gifts — Retail value (or market if absent) of items received for free. They contribute to the total value but not to the ROI %.
Sets / Minifigs — Breakdown of value and ROI by sub-category, calculated the same way as the total.
Dashboard
The value evolution chart
This chart shows how your collection's value has evolved over time.
Value evolution
Start of period
11 250 €
Today
12 450 €
Change
+1 200 € (+10,7%)
The curve — Total market value of your collection day by day, calculated from automatic daily snapshots.
The periods (1M, 3M, 6M, 1Y, Max) — "Max" shows all available history since you signed up.
Start / Today / Change — Numerical summary of the selected period: initial value, current value, and absolute + relative gain.
Dashboard
The Portfolio Health Score
A synthetic indicator that evaluates the overall performance of your collection out of 100 points.
Portfolio Health Score
Overall performance out of 100
Avg ROI
▲ +36,2%
Profitable items
78%
Total gain
+1 450 €
Score /100 — Composite indicator: avg ROI × 0.5 (up to 60 pts) + profitable item ratio × 40 (up to 40 pts). ≥ 70 = excellent · 40–69 = fair · < 40 = watch out.
ROI avg +36,2% — Arithmetic mean of individual item ROIs (unweighted by value). Different from portfolio ROI: a profitable polybag counts as much as a flagship.
78% profitable items — Share of your collection where market value exceeds purchase price. Measures the consistency of your choices, regardless of amounts.
Total gain — Sum of unrealized gains of all items in profit. Corresponds to what you would recover by selling everything at current market price, above your investment.
Item detail
The market price comparison
Each item has a block comparing the different available price sources.
Market position
Purchase price
400,00 €
Jan 15, 2024
Retail price
449,99 €
Brickset · PPC
New sealed
520,00 €
BrickLink · your condition
Used
340,00 €
BrickLink · 30d avg
Purchased at 400 € · current value 520 €
+30%
Purchase price — What you paid at acquisition. Used as the basis to calculate your personal ROI.
Retail price — Official LEGO store price (Brickset source). Launch reference — useful to know if you bought below or above retail.
New sealed / Used — Average BrickLink price (completed sales + listings) updated automatically. The progress bar visually compares against the highest of the 4 prices.
Badge "Your condition" — The highlighted price corresponds to the currently declared condition of your item (sealed → new, built → used).
The summary line — Summarises in one sentence: purchase price, current value for your condition, and your immediate personal ROI.
Inventory
The collection table
Each row represents an item. Here is how to read the important columns.
Item
Invested
Market
ROI
Rivendell
10316 · Icons
499 €
540 €
+8,2%
Millennium Falcon ×2
×275192 · Star Wars
900 €
1 220 €
+35,6%
Aragorn King Elessar
FIG.sw1234 · Minifig
0 €
—
—
×2 — Purple badge: you own multiple copies of this item. They are merged onto one row. The displayed values are the totals for both copies.
FIG. — Amber badge: this is a standalone minifig, not a set.
Invested — Declared purchase price. If €0, the item is a gift — it does not contribute to ROI but its market value is counted in the total.
Market — Current BrickLink price according to the item's condition. "—" if no price available (rate limit or set too recent).
ROI — (Market − Invested) ÷ Invested × 100. "—" if purchase price is 0 (division impossible) or market price is absent.
Frequently asked questions.
Is Cault really free?
Cault is in launch — payments are not yet available. The first 50 users get full free access for life (inventory, market prices, finances, alerts). Beyond that, paid plans will open soon.
Are BrickLink prices reliable?
Yes. BrickLink is the world reference for the LEGO secondary market — it's the same platform professional sellers use. Cault queries their official API directly.
What's the difference between Brickset and BrickLink?
BrickLink provides secondary market prices (resale between individuals and professionals). Brickset provides the official LEGO.com retail price as well as launch and retirement dates. Both are complementary.
Can I force a price update?
Yes. On each item, a Refresh button triggers an immediate update from BrickLink and Brickset. Otherwise, prices update automatically every 48h.
Does the ROI account for selling fees?
The ROI shown in the collection is calculated on market price vs purchase price — without fees. During an actual sale, you enter the net received price and platform fees separately: the final P&L accounts for them. The CSV tax export includes this data for each disposal.
Can I export my data for my tax return?
Yes. From the Transactions page, the "CSV Tax Export" button generates a table of all your disposals for the chosen year: purchase date, purchase price, sale date, sale price, net gain. This document is not contractual — have it validated by your tax advisor.
You're ready. Get started.
Free. 5 minutes to set up. Your first ROI displayed immediately.