How FangTrack Works

The 60-second version

FangTrack scrapes 77 invertebrate vendors, pulls every live listing, and compares each one against the whole market and its own price history. It then tags each listing with a deal rating so you can see, at a glance, what's genuinely a good value versus what's overpriced. Add species you want to a Watchlist and FangTrack tells you the moment one shows up at your target price.

The data refreshes automatically on a schedule — you don't run anything. Just open Deals to see the latest, or add species to your Watchlist to be alerted.

What the badges mean

Ratings are always like-for-like: a listing is only compared with the same species, the same sex group (female / male / mature male / unsexed are kept separate), and the same size class. Captive-bred, wild-caught, and unstated-source listings all compete together — most vendors never state a source, so excluding them would knock the majority of honest listings out of contention. We show the CB / WC / ? tag on every listing as information, but it carries no weight in the score. Always confirm the source with the seller and choose captive-bred (CB) whenever possible.

Rarity tiers

A separate signal from deals. Every species is percentile-ranked across the whole tracked catalog by how few sellers carry it — rarest at the top. The named tier answers "how hard is this to find right now?"

The dashboard, tile by tile

The tiles across the top are live counts from the most recent crawl of the vendor websites only — private-seller lists are never counted here. Every tile is clickable and opens the Deals page pre-filtered to it.

The Top Deals list below the tiles is the market's best offers right now: every 🔥 Fire and 💎💎 Exceptional listing, shown by lowest ask first. If it's on that list, it's either an all-time-low delivered price or at least 40% under the median — never just "inexpensive." As always, confirm the price and source on the vendor's own site before buying.

The tabs

Rarity & source columns

Rarity (x/10) — how uncommon a species (and size class) is across the tracked market. Higher = fewer sellers carry it.

CB / WC — captive-bred vs. wild-caught, inferred from the listing. They're never price-compared to each other.

The trait badges on each spider card

Each species page shows up to six at-a-glance badges — the husbandry and safety facts a buyer asks first. They're researched per species (genus defaults with species-level corrections), and always appear in the same order. Hover any badge for the detail.

These are general guidance from reputable care sheets, not a substitute for researching your specific animal — always confirm care with the seller and a trusted source before buying. Scorpions and jumping spiders show a trimmed set suited to them.

How the market price is calculated

Everything FangTrack sees is an asking price, not a completed sale — no vendor tells us what an animal finally sold for. So the market price for a species is the trimmed median of recent asks: we sort them, drop the single highest and single lowest, and take the middle of what remains. One eye-watering listing therefore cannot drag the number up, and one clearance sling cannot drag it down. Where we have fewer than four asks to work with there is nothing safe to trim, so it is the plain median of what we have.

A small number of sellers are excluded from the price statistics. Some shops deal mainly in premium display specimens — hand-picked adult females, communal groups, animals sold with a full enclosure — and their asks routinely run several times what the same species goes for elsewhere. Those are real listings and real animals, but they describe a different product, so letting them into the median would publish a price almost nobody is actually paying. On a species where such a shop is the only seller, its ask would simply become the market price.

So their listings still appear on the species page and in Deals, with a link straight to the seller — we are not hiding anyone, and if that specimen is what you want, you should be able to find and buy it. They are only kept out of the calculated figures: market price, lowest ask, all-time low, the 90-day range, and the movers and records on the dashboard. That is why a species page can show more listings in its table than the count in the stat cards above it, and the table says so when it happens.

It is a short, reviewed list rather than an automatic rule. We identify candidates by comparing a seller's asks against the market price for the same species across every other vendor: a normal shop sits at roughly 1× the market, and the excluded ones sit at 3× or more with a large share of listings above 8×. Being excluded is not a judgement about a seller’s honesty or their animals — it means their prices answer a different question than the one this number is trying to answer.

How your collection is valued

Tarantula prices swing enormously with sex and size — a confirmed adult female can be worth 3–6× an unsexed sling of the same species. So FangTrack values every animal in your collection like-for-like instead of using one blended average:

1. It finds the current in-stock listings of the same species.
2. It narrows to ones matching your animal's sex (female / male / unsexed) and then its size class (sling / juvenile / sub-adult / adult).
3. Your value is the median of those matching listings. The small grey note under each Market price on your Collection page tells you exactly what it was compared to — e.g. "adult female comps (5)".
4. If there aren't at least two matching listings, it widens the comparison (same sex, any size → same size, any sex → the species-wide market median) and labels it "market median" so you know it's an estimate.

Worked example. A Green Bottle Blue: as an unsexed 1" sling it's worth about $60 (what slings actually list for); as a confirmed adult female it's valued near $250, because that's the median of the adult-female GBBs listed right now — not the ~$85 you'd get by averaging every GBB of every size and sex together.

It's a market estimate from live asking prices, not a formal appraisal or a guaranteed sale price — the more precisely you record each animal's sex and size, the sharper the estimate. Purchase prices you enter stay private to you.