Say goodbye to bad buys.

Pre-Check is a mobile app for eBay resellers that gives you real-time market data before you buy — so you know if an item is worth buying before it's in your cart. 

Search by photo or search by text, and Pre-Check pulls live eBay data to show you supply and demand, sell-through rate and profitability at a glance.

Google Lens is great for quickly identifying the name of a physical product. In some cases, Google Lens search results even includes links to various marketplaces with active listings - allowing you to quickly identify an active listing comp.

While product identification and a single active listing comp is helpful, it doesn't provide the proper amount of context to determine if the item is likely to be profitable, and if or when it is likely to sell.

In addition to Product identification and a single active listing comp, Pre-Check provides the following:

1.) Up to 4 image search vs. a single image, which makes our search function more accurate

2.) 50 Active Listing Comps sorted by Newly Listed or by Price (High or Low)

3.) Direct link to eBay sold listings for # Sold (Demand)

4.) Sell-Through Rates

5.) Active Listing Velocity

6.) Number of New Listings in the last 24 hours

7.) Total Number of Active Listings (Supply)

8.) Real-time Average List Prices

9.) High and Low-End Price Range

10.) Cost of Good input

11.) Max Buy Price recommendation to remain profitable

12.) Estimated Profit Projections

13.) Estimated ROI Projections

14.) Active Listing Price Distribution chart to find the sweet spot for pricing your item

15.) Scans History to review performance metrics for previously searched items

16.) Hauls to establish a virtual cart that mimics your real world cart, to verify # of items in cart, total spend against total budget, profit, and ROI

17.) Custom Settings to establish the inputs needed to accurately calculate sell-through rate, velocity, profitability, and ROI

When Google Lens executes an image search, it's only identifying the product and looking for related webpages using a single image search.

When Pre-Check executes an image search, it's identifying the product with up to 4 images, looking for related products on eBay that strictly match the item from the picture(s) provided, serving up the 50 most recently listed active listings, populating the Active Listing Price Distribution chart, and calculating the custom metrics.

All of those additional outputs increases the processing time to populate results. 

In general, an image search should take no longer than 2 - 4 seconds.

Whether you search by photo or by text, eBay's native search function is built to do one thing: show you listings that match. It's a discovery tool — it finds items, but it doesn't give you the information you need to make a data-driven purchasing decision for reselling.

Furthermore, instead of just getting a list of similar listings, with Pre-Check, you get sell-through rate, velocity, average list price, and a recommended max buy price, plus estimated profit and ROI calculated against your actual cost of good.

In short: eBay search finds similar listings. Pre-Check tells you whether or not to buy.

It goes without saying, but we have to feed our families.

On a serious note, the ongoing costs of app development, user support, future development, and infrastructure costs are recurring expenses that must be recouped so that this app can remain active and improved over time.

Our committment to you is that as long as we maintain an active user base, we will ensure that Pre-Check remains stable with value-added improvements along the way.

This is actually a good thing. It means that the item you found is more likely trash than treasure. By discovering this using Pre-Check, you have just saved yourself from a bad buy.

Success in reselling is not just about knowing what to buy. What's more important is knowing what NOT to buy.

Buying inventory with little or no demand is the leading cause of failure that causes most resellers to quit prematurely, so the last thing that you want to do as a reseller is a buy a bunch of junk based on vibes and personal attachments. That is a recipe for a financial disaster and a house full of unsellable inventory.

If you run an Image Search (or a Text Search) and you're not getting many matches, that is a reflection of low supply, which often equates to low demand, which yields a negative profit (loss).

In some cases, a search that yields little to no results could mean that the item is rare, and therefore has value, but without being able to verify it with active (supply) and sold (demand) listings, you're gambling away your hard earned money.

The moment you violate the value of the Pre-Check app, and you begin buying items that don't meet your metrics, is the moment you will do it again, and again, until you lose hope, run out of money, and run out of space to store inventory.

eBay is currently the only peer-to-peer online marketplace with an API that provides app and web developers with direct real-time access to active listings data.

Poshmark, Depop, Vinted, and other major marketplaces do not provide developer access to their listings data. 

As a result, apps similar to Pre-Check that provide resellers with sold listings data, such as number of items sold or sell-through rate, rely on direct or scraped data from 3rd parties, or proprietary data they develop through proxies and in-house mathematical formulas, all of which are illegal and/or inaccurate.

If you sell on Poshmark, Depop or other online marketplaces, or you cross-list there in addition to eBay, Pre-Check is a great proxy (estimate) for sales performance metrics on other platforms.

That being said, if you run a search in Pre-Check for an item that has a low sell-through rate on eBay (< 40%), in theory, your actual sell-through rate across all platforms could double or triple that number if you're double or tripling your potential reach by cross-listing on other platforms.

Disclaimer: Sell-through rate and any other related metrics are based on probabilities, not guaranteed outcomes.

Sell-Through Rate (STR) tells you how quickly items are actually selling — not just how many are listed, but how much real demand there is for them. A higher STR means similar items are moving fast; a low STR means they're sitting.

Why it matters: a good price doesn't automatically mean a good buy. An item can be cheap and still be a bad purchase if almost nothing like it is selling. STR is what separates "cheap" from "sellable" — it's the difference between a deal and dead inventory.

In Pre-Check, STR is calculated automatically every time you scan an item, pulled directly from live eBay data — no manual research required.

There isn't one universal way to calculate Sell-Through Rate, so Pre-Check gives you the two that are most widely used:

STR V1 (sold ÷ (sold + active) is the industry-standard formula, and the one we use as your primary number. It shows what percentage of all the listings out there — sold and still active — actually ended in a sale.

STR V2 (sold ÷ active) is a secondary, more aggressive view. It compares sold items directly against what's currently active, which can highlight fast-moving demand that V1 sometimes understates.

We show both because they can tell slightly different stories — V1 gives you the steadier, industry-comparable number, while V2 can surface momentum sooner. Looking at them together gives you a fuller picture than either one alone.

STR benchmarks can vary somewhat by category, but as a general guide:

Above 40% is generally considered a healthy, sellable rate — items in this range are moving at a pace worth sourcing for.

Below that signals weaker demand — the item may be overpriced relative to what buyers are actually paying, or there's more supply than demand can absorb right now.

When you think about STR, you also need to consider how much space you have to store inventory, whether or not you cross-list on multiple platforms, and how quickly you would like to recoup your money from the sale of an item after you purchase it.

As an example, if you live in a studio apartment and you plan on storing inventory there, buying lower STR items will eventually turn your apartment into a hoarder's house. Items will sell slowly, if at all, and it will take a longer amount of time to recoup your money from the investment you put into inventory.

Conversely, if you live in a single-family home with an empty bedroom or basement and reselling income is just a supplement, you have enough space and financial breathing room to justify an accumulation of lower STR items.

When it comes to cross-listing, STR across multiple platforms could potentially be double or triple the eBay number provided from Pre-Check, since your reach and visibility is somewhere between 100 - 300% higher. This is particularly the case with apparel cross-listing on Poshmark, Depop, Mercari, Whatnot, etc. In that case, lowering your threshold for STR may be viable.

It's important to understand that there's no single "safe" number that applies to every category and every individual reseller. Use STR as a relative signal alongside velocity and estimated profit, not as a standalone yes/no filter.

In February 2025, eBay removed public access to sold and completed listings data from its developer API. That means no app — including Pre-Check — can pull historical sold counts automatically anymore.

To still give you accurate Sell-Through Rate and demand data, Pre-Check asks you to manually enter the number of sold listings you see on eBay. It's a small extra step, but it keeps your data honest.

Some apps work around this by using illegally scraped data or third-party sources, which is often outdated, inaccurate, and a breach of eBay's Terms of Service. We'd rather ask you for 3 seconds of input than hand you numbers we can't stand behind.

There's no single STR minimum that works for everyone — the right threshold depends on your own situation, not just the item. A few things to factor in before picking a number:

1.) Storage space. If inventory is piling up in a studio apartment or a spare closet, a low STR minimum means slow-moving items accumulate fast — and you can end up with cash tied up in things that just sit. If you've got a basement or a dedicated space, you can afford to be more patient with lower-STR items.

2.) Cross-listing. If you only sell on eBay, use Pre-Check's STR number as-is. If you cross-list on Poshmark, Depop, Mercari, Whatnot, or similar, your real sell-through is likely higher than what eBay alone shows — often 100–300% more reach — so you may be able to comfortably lower your STR minimum and still move inventory at a healthy pace.

3.) How fast you want your money back. A higher STR minimum means faster turnover and quicker cash recovery on what you spend. A lower minimum means more patience, but also more opportunities, since you're not filtering out as many items.

As a starting point, many resellers use something in the 20–40% range as a baseline minimum, then adjust up or down based on the factors above. There's no universally "correct" setting — treat your STR minimum as a dial you tune to your own space, platforms, and cash-flow needs, not a fixed rule.

Start by thinking through everything one item actually costs you in time — not just money. Finding it, cleaning it if it needs it, photographing it, writing the listing, packaging it, and getting it to the post office all add up. A single item might take you 10–15 minutes of hands-on work from start to shipped, sometimes more.

Now think about how much time you actually have available to dedicate to processing inventory. If you've got 2 hours a day and each item takes 15 minutes to process, that's roughly 8 items a day, realistically — not an unlimited pipeline. That number is your ceiling, whether you want it to be or not.

Once you know your time budget, the math gets simple: your time is worth something, whether or not you're currently pricing it that way. If you're spending 15 minutes on an item that nets you $4 in profit, you're paying yourself $16/hour before gas, packaging, and fees eat into it further — and that's before anything goes wrong. Set a profit minimum that reflects what your time is actually worth to you, not just "better than nothing."

ROI matters separately from profit, because it's about risk, not just reward. When you buy inventory, you're tying up cash — and some items sell in a week, some take months, and some never sell at all. Your ROI minimum needs to be high enough to compensate you for that uncertainty. A low-ROI item that takes 6 months to sell (or doesn't sell) isn't just a wasted purchase — it's cash that could have gone toward inventory that actually moved.

Put together: your profit minimum should reflect what your time per item is worth, and your ROI minimum should reflect the risk of your money sitting in unsold inventory. Neither number is universal — it depends on your own processing speed, how much time you have, and how much risk you're willing to carry — but both should be high enough that a "yes" on Pre-Check actually means the item is worth your time and your money, not just technically profitable on paper.

If you find that nothing, or very few items you search for in Pre-Check is hitting your profit or ROI minimums, that's usually a sign that your cost of goods is too high — not that your targets are wrong. Rather than lowering your minimums to force more "yeses," it's worth looking into other sourcing opportunities that get you better acquisition costs instead.

The confetti animation in Pre-Check is a "triple threat" signal — it fires only when a listing simultaneously clears all three of your core thresholds:

1. Sell-Through Rate (STR V1 and STR V2) meets your target
2. Estimated Profit meets your target
3. Estimated ROI meets your target

When all three line up, Pre-Check treats that as a standout find rather than a merely passable one, and the confetti is the visual cue to grab your attention so you don't scroll past it. Items that clear only one or two of the thresholds still show as positive/green where applicable, but they won't trigger confetti — that's reserved for the full sweep.

Yes. The Hauls feature lets you track an entire sourcing trip — your budget, every item you've added to your cart, total spend, and your estimated profit and ROI for the whole haul, not just one piece at a time.

Individual item performance metrics can be found on the Scans tab.

Pre-Check is built for in-the-moment sourcing decisions wherever you shop — thrift stores, retail clearance, estate sales, outlet stores, garage sales, rag houses, online arbitrage, or any other sourcing channel.

This is a debate that will persist until the end of time, but here's our take:

Many consumers who are unfamilar with the supply chain logistics of second-hand merchandise, are unaware that items that are donated to places like thrift stores go through the following cycle:

1. Filtered and sorted upon intake to separate sellable vs. unsellable (damaged) items

2. Placed in brick and mortar stores for sale

3. High-end items are listed for sale on direct websites and/or 3rd party sites like eBay

4. Unsold in-store merchandise or excess unprocessed donations are sold in outlet stores in bins or gaylords, or to smaller independent thrift stores

5. Whatever else is leftover is dumped in landfills or sold overseas for pennies on the dollar

So no, reselling is not wrong or immoral, as donation recipients (thrift stores) go through a multi-step process to prevent as much second-hand inventory from entering landfills as possible.

It is true that reselling increases the cost of goods at thrift stores, which negatively impacts lower income shoppers. However, there would still be a tremendous surplus of second hand items entering landfills if items were priced lower, as there simply isn't enough demand to meet the excess supply of donated items.

Furthermore, the more money a thrift store can earn in revenue, the more they can contribute to accomplishing their goals: work programs, homeless shelters, food panty programs, religious initiatives, etc.