How FangTrack Works
What every number here means, where it comes from, and what it does not claim.
The 60-second version
FangTrack scrapes 75 invertebrate vendors, pulls every live listing, and compares each one with what is typically asked for the same animal at the same size and sex. Where it can make that comparison it grades the listing, so a low ask stands out.
The data refreshes every day on its own. Open Deals to see the latest, or add a species to your Watchlist and it is flagged after the next crawl that finds one at your price.
FangTrack only ever sees asking prices, never completed sales. No vendor tells us what an animal sold for, so every figure here describes what is being asked.
What the badges mean
- 🔥
- Fire deal — the lowest in-stock ask per animal, before shipping, that we have recorded for that species and sex and, for tarantulas, life stage. The listing has to match or beat that record and sit at or below its Typical here, and at least two shops must have listed there. A pack never qualifies. It replaces the grade: a listing shows one badge.
- 💎💎
- Exceptional — at least 40% below its Typical here.
- 💎
- Strong — 20% to 40% below.
- 👍
- Fair — from 20% below to 20% above.
- 👎
- Above market — more than 20% above.
- Not graded
- Not graded — not enough to compare: no size we could read, a listing of several animals, a listing of eggs, a species only one shop lists, too little for the price model to go on at that size and sex, a premium color form that has no page of its own yet, or a species the model does not cover, which includes every isopod and roach. No percentage is shown, and it is not a mark against the listing. On Deals, hover the badge for the reason.
The cut-offs are wide on purpose. Measured in August 2026, the same animal at the same size was commonly listed at about 2× the price by one seller as by another.
Rarity
Rarity is supply, and only supply: the tier is how many sellers have ever carried a species, and for a single seller, how many separate listings. Price is not part of it, and neither is how recently it appeared. Tiers are given to tarantula species only.
1 seller, 1 listing
Almost never listed. Usually one animal at one seller.
1 seller with 2+ listings, or 2 sellers
Only a handful of sellers have ever carried it.
3-4 sellers
A few sellers, and it does not stay listed long.
5-8 sellers
Around, but you will shop several sellers to find one.
9-15 sellers
Usually somebody has one.
16+ sellers
Everywhere, almost always in stock.
Listings also carry a 1–10 score, the same signal on a finer scale, so Deals can sort and filter by it. Every group has a score; only tarantulas have a tier. Both describe the market we can see, not the whole hobby.
Captive-bred, wild-caught, and how we know
Every listing carries a source tag: CB captive-bred, WC wild-caught, long-term captives included, or ? when nobody has told us. A small ° means it came from the shop's policy or from the animal's size, not from the listing itself.
How we decide, in priority order
- The listing says so
- The title, variant or size text. A labeled field such as "CB/WC: WC" is read by the value after the colon.
- The description says so
- Clear phrases only, such as "captive bred". A bare "CB", "F2" or "breeder" in sales copy does not count.
- The seller's policy
- A captive-bred-only policy read from the shop's own pages, or confirmed with the shop by a person.
- Inferred juvenile
- Under ¾", or under a third of the largest one of its species on offer: nobody field-collects slings that size commercially.
A statement beats a policy, and a policy beats an inference. Where none applies the tag stays ?.
What it changes
Source has no weight in the typical advertised price, the rarity tier or what your collection lists for. It counts in one place: when the seller's own title or variant says wild-caught, the grade compares the listing with wild-caught prices, which currently run about 14% lower. A source we inferred, or took from a description or a shop's policy, never moves a grade.
Always confirm the source with the seller, and choose captive-bred (CB) whenever possible.
The tabs
One page sits off the menu: Market Records.
The trait badges on a species page
Six badges on a tarantula's page, always in this order. Hover one for the detail. They resolve species-first and fall back to the genus.
- New World Old World
- New World species have urticating hairs but milder venom; Old World have no hairs, more potent venom, and tend to be faster and more defensive.
- Terrestrial Arboreal Fossorial Semi-arboreal
- Where it lives, which decides the enclosure: floor space, height, or deep substrate.
- Dwarf Medium Large
- Adult size class, not the size of the animal in a listing.
- Docile Skittish Defensive
- Temperament. Green tolerates maintenance; red readily throws a threat posture.
- Beginner Intermediate Advanced
- Venom, speed and husbandry rolled into one rating, from published care guidance.
- Tropical Temperate Arid
- The climate to keep it in.
Tarantulas only: other groups show no badges, and neither does a tarantula we have no data for. This is general guidance from care sheets, not a substitute for researching your own animal.
How every number here is worked out
How prices work. Every price here is an ask, not a sale. Each listing counts once, at its newest ask, and each shop counts as one voice for a species. Listings of several animals are left out, except animals sold by count, which are priced per dozen.
Every shop we track is included.
Method changes — 2026-09-28: each listing is graded against the typical price for its own size and sex, and every shop we track counts. Figures from before that day used the previous rules.
Like for like. A listing is only compared with the same species, the same sex group (female, male, mature male, unsexed) and its own size on the species' price curve, never with the species as a whole. A seller's hedge — probable, likely or suspected female — is read as unsexed.
- Typical advertised price
- A real ask, to the nearest dollar, before shipping, for one unsexed animal. Tarantulas with a known adult size are compared as unsexed slings, or as the stage most shops list when no sling is listed. Three or more shops within a dollar of each other: that price. Otherwise those tarantulas show the middle shop's ask, and every other species the range of current asks. One shop asking is named as one shop. Never a modeled figure, and each shop counts once.
- Typical here
- The price model's typical for a listing's own size and sex, refitted every night across every shop's asks. Each shop's own level and slope stay inside the model, so a shop that prices high does not move what “typical” means for everyone else. Commonly span, in the price box, is the middle 80% of asks the model expects.
- Lowest ask, all-time low, 90-day range
- The tiles on a species page cover the whole species, every size and sex together. Lowest ask is the lowest in-stock ask right now; the all-time low and high are the extremes across all our crawls; the 90-day range is the same pair over 90 days. A listing of several animals is left out of all of them. A species sold by count is priced per dozen instead, and eggs per 10.
- Price per dozen
- Isopods, roaches, and other invertebrates only ever listed in lots of 4 or more, are priced per dozen: a lot's price, divided by its count, times twelve. Eggs are priced per 10 the same way. The price box takes each shop's lot nearest the dozen (or ten), then three shops within a dollar, else the middle shop. A listing of fewer than 4 animals, or one that states no count, is never priced.
- Size
- The size the seller states, in inches. A bare stage word, such as sling or adult, is placed at a standard size for that stage. Jumping spiders are sized by stage, and isopods carry no size. A pack count, a molt stage, an enclosure, or a size no animal of that group could reach is left blank rather than guessed — and no size means Not graded.
- Landed
- The ask plus the flat shipping rate we hold for that shop, read from the shop's own policy where it posts one, with its free-shipping threshold applied; for a pack, the whole box. A shop that calculates postage at checkout gets no landed figure: the cell shows ❓, not a rate we made up.
- Biggest jump / drop
- The exact same single-animal listing — same page, variant, size, sex and seller — asking over 3% more or less than on that seller's last crawl from an earlier day. A fall of more than 95% or a rise of more than ten times is treated as a data error. When no single listing moved, it is the largest change in a species' median single-animal price between two crawl days.
- Market Records
- Named superlatives from the live listings, single animals only. The ones a thin sample could win have a floor: a mean ask of $25 or more for most volatile, five species for priciest genus, three sellers for widest price gap, and 30 observations for rarest. A record we can't back is left out.
- Bundle plans
- Three, side by side: Lowest total, Fewest boxes, and Best data, which uses only sellers who publish a shipping rate. A delivered total prints only when every box has a published rate.
What your collection lists for
Each animal is priced at the typical advertised price for its own species, sex and size, from the same price model that grades listings — a confirmed adult female is not priced like a sling. An animal with no size recorded takes the species' typical advertised price instead where one is named; where the shops do not agree on one, it shows a dash and is left out of the total. The small gray note under each figure says which.
It is a reading of today's asks, not an appraisal and not a sale price. The range under the total is the middle 80% of 400 draws of the fitted price lines: how sure the model is of these typicals, not how far shops vary from each other. What you paid is never shown to another user.
FAQ
How often does the data update?
Every day, on its own. FangTrack waits at least 2 seconds between requests to each vendor, one request at a time per vendor and up to 5 vendors in parallel, and longer where a vendor asks for longer. If a shop's crawl fails, its last good prices stay up. We check a shop's robots.txt before adding it, our nightly audit checks again, and a shop that asks not to be crawled is not crawled.
What counts as a listing?
One in-stock variant. A product offered as 1" unsexed, 2" female, and 3" male is three listings, each with its own price. When a variant goes away it stops counting, and its price history is kept.
Why don't I see feeders, enclosures, substrate, or merch?
FangTrack tracks live invertebrates only. Supplies, feeders, decor, plants, apparel and art prints are filtered out, and so is a listing whose title never prints a scientific name we recognize: without one there is nothing to match it to.
Does a person ever decide what is listed?
Yes, and we would rather say so than let a rule take the credit. People keep the lists the rules run on: which genera count, which product names are removed by hand (a book, a torch lighter, a ball python), which misspellings and old names merge onto one species page, and a handful of common names keyed to their species. A price under $1 or over $10,000 is not listed. If a listing of yours is missing, Feedback reaches a person who can tell you why.
How do private seller lists work?
On Private Sales, paste a seller's price list or upload it as a file, and add their contact details. It becomes listings only you can see, and it can never move a public number. Hide private sellers in Account hides them from your own view.
Does FangTrack sell my data or take money to boost rankings?
No. No ranking has any knowledge of a commercial relationship — there is nothing to buy. What you import and what you paid are never shown to another user.
Something on this page looks wrong to you. What then?
Tell us — Feedback reaches a person. If a price, a size or a source tag on your own shop is wrong, we would rather hear it from you than publish it. Any vendor can also ask us to stop crawling them; a person reads every request and acts on it by hand.
How FangTrack makes money
It doesn't.
No ads, no affiliate links, no fees from sellers. Links go to the vendor's own page, at the vendor's price; most pass through FangTrack first so we can count the visit.
Donations are welcome, never required.
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