Checkthevendor.com is an independent peptide-vendor grading and comparison site. We do not sell peptides. We rate the vendors who do, so you can compare them on the things that actually matter.
This page explains exactly how a grade is built, what the evidence is, and how to read a scorecard. Our goal is that you could follow the same steps and reach the same result.
One important boundary up front: we grade vendor quality only. We do not assess the safety, efficacy, legality, or suitability of any peptide for any purpose. Nothing on this site is medical, dosing, or health advice.
Our mission and what “independent” means
We are not a vendor. We have no peptide inventory to move and no house brand to protect.
Our job is to look at the vendors in this market, apply the same rubric to each one, and turn what we find into a clear, comparable grade. Every grade is our editorial opinion, grounded in disclosed, dated facts that we link so you can check our work.
The eight criteria and their weights
Each vendor is scored on eight criteria. The weights sum to 100% and reflect how much each factor tells you about vendor quality. We tag each criterion by how it is assessed: measured (verifiable fact), editorial (labelled opinion), or mixed (a blend of both).
| Weight | Criterion | What it looks at | Type |
|---|---|---|---|
| 25% | Third-Party Lab Testing & COA Verification | Whether an independent lab has tested the product, and whether published Certificates of Analysis are current and tied to the named lab and lot | Measured |
| 18% | Measured Purity & Contaminant Profile | The purity result and contaminant findings from testing | Measured |
| 12% | Transparency & Disclosure | How openly the vendor discloses sourcing, testing, identity, and policies | Mixed |
| 12% | Reputation & Customer Service | The vendor’s track record with buyers and how it handles support and problems | Editorial |
| 10% | Pricing & Value | Price relative to what you actually get, including verified purity | Measured |
| 8% | Shipping, Packaging & Fulfilment | Order accuracy, packaging quality, and delivery reliability | Mixed |
| 8% | Payment Options & Checkout Trust | The range of payment methods and the trust signals at checkout | Mixed |
| 7% | Website & Operational Trust Signals | Site quality and operational signals that indicate a legitimate, functioning business | Editorial |
The first two criteria — independent testing and measured purity — carry the most weight on purpose. They are the hardest things for a vendor to misrepresent and among the most useful things for you to know about a vendor.
From 0-100 to a letter grade
Each criterion is scored from 0 to 100 against a published rubric. We multiply each score by its weight, sum the results into a single 0-100 composite, and map that composite to a letter grade:
| Grade | Composite |
|---|---|
| A+ | 97-100 |
| A | 93-96 |
| A- | 90-92 |
| B+ | 87-89 |
| B | 83-86 |
| B- | 80-82 |
| C+ | 77-79 |
| C | 73-76 |
| C- | 70-72 |
| D+ | 67-69 |
| D | 63-66 |
| D- | 60-62 |
| F | below 60 |
How vendors are ranked
Our leaderboard orders vendors by their composite score, highest first, within each category we cover. The ranking contains no extra ingredient — it is the same grades you see on each scorecard, simply sorted. Where two vendors tie on score, the one with the higher confidence label ranks above. Sponsored placements never enter this ranking (see How money works here).
The integrity gate
Some findings matter more than any weighted average. The integrity gate is a binding override that sits on top of the composite score:
- A vendor with no independent third-party COA cannot score above the D band — capped at a D+ (69/100) — regardless of how well it does elsewhere.
- A vendor we find to be publishing fabricated or reused COAs, or fake reviews, is capped at F and flagged.
The gate exists because the point of a grade is trust. In our view, a vendor that cannot show independent proof of what it sells, or that has misrepresented that proof, has not earned a passing trust grade no matter how polished the website looks. Where we apply the gate, we state the specific, dated observation behind it and link the evidence, so you can see what we saw and reach your own conclusion.
Confidence labels
A grade is only as good as the evidence behind it. Alongside every grade we publish a confidence label so you know how much data it rests on:
- High — at least one independent test or per-lot COA in the past 12 months, and at least 20 independent community data points.
- Medium — an independent COA is present but sparse, or there are 5 to 19 community data points.
- Limited / provisional — vendor-supplied data only, fewer than 5 data points, or any criterion left unscored.
A high grade with a Limited label means “looks good so far, but we don’t have much to go on yet.” Read the label as carefully as you read the letter.
How we source evidence
Every score is built from one or more of three evidence types:
- Independent test-buys. We buy products as an ordinary customer and send them to an independent lab (for example, Janoshik) for analysis. The vendor does not know which order is ours.
- Vendor-published COAs. Where a vendor publishes Certificates of Analysis, we verify them against the named lab and the stated lot rather than taking them at face value.
- Community-reputation sampling. We sample buyer reputation using a documented method: named sources, a stated date range, a minimum number of data points, and explicit exclusion of outliers and suspected astroturfing.
Measured versus editorial
Every individual score is tagged so you always know what kind of claim you are reading:
- Measured scores are verifiable facts — a lab result, a published price, a COA that checks out. The evidence is linked.
- Editorial scores are our labelled opinion, formed from disclosed facts. We tell you what we observed and why we weighed it the way we did.
Where a criterion is mixed, we separate the factual part from the judgement part within the scorecard.
We state verifiable observations and let you draw your own conclusions. We do not present unprovable accusations as fact. If a vendor’s own materials make a claim — for example, a statement about the purpose for which it says its products are sold — we may report that as a fact about what the vendor says. We report such claims; we do not adopt them as our own framing.
How often we re-review
Grades go stale if they are never revisited. Our re-review cadence:
- Pricing — quarterly.
- COA and purity — with each new batch; otherwise every 6 months, with an independent test-buy refresh at least annually.
- Reputation — every 6 months.
- Full re-grade — annually, or sooner if our methodology changes.
Each scorecard shows when its evidence was last refreshed.
How money works here
We make money through affiliate links and clearly-labelled sponsored placements. Here is the hard rule that governs all of it:
Money never affects a grade or a ranking. The same rubric applies to paying and non-paying vendors alike. Sponsored slots are visibly labelled and kept out of the merit ranking. Affiliate links are disclosed.
If a vendor pays us and still earns a poor grade, it earns a poor grade. There is no version of this where money changes the score.
How to read a scorecard
When you open a vendor’s scorecard, here is the quick way to read it:
- Start with the letter grade and the confidence label together. A B+ at High confidence is a very different thing from a B+ at Limited confidence.
- Check the integrity gate first. If a vendor is capped or flagged, the detail explains why.
- Look at the top two criteria — independent testing and measured purity. They carry the most weight and the most reliable evidence.
- Note the measured-vs-editorial tags. Measured scores are facts with linked evidence; editorial scores are our reasoned opinion.
- Read the dates. Check when the evidence was last refreshed against our cadence above.
Fairness and corrections
Every vendor we grade gets a free right of reply. If you are a vendor and believe we have a fact wrong, you can use our corrections process and we will review the evidence and update the scorecard where warranted. Grades can move up or down when the facts change.
Methodology version 1.0 — published 29 June 2026. Material changes to this methodology will be versioned and dated here, and will trigger a full re-grade.