Trust and transparency

Trust is the product

Here is everything you need to check for yourself what we do: how we verify purchases, how we calculate the index, what we do against manipulation and what we never do. The rating is not for sale.

companies

on the platform, excluding suspended ones

venues

23 enrolled · 8 with the badge

4,394

verified ratings

receipts rejected

outside the window, below the minimum, unrecognised venue

duplicates blocked

one receipt, one rating

customer reports

1 active integrity reports

How we verify a purchase

The QR code on a Bulgarian receipt contains five things: fiscal memory number, receipt number, date, time and amount. Nothing else. From these we identify the day and the legal entity (the company), and from the fiscal device, the venue. That is why every rating gets a trust level based on what we know.

Level	What we have	In the index
A · verified	Valid QR code, a device confirmed by a registered company, scanned within 72 hours and near the venue	Full weight
B · venue recognised	Valid QR code, the venue is recognised (or named by the customer), but the device is not yet confirmed	Full weight once the device is confirmed
C · no proof	No readable QR code, the receipt is old or the venue is unknown	Not included. It still goes to the company as feedback.

We store only a fingerprint of the receipt (SHA-256 of the memory number, receipt number, time and amount), the venue, the price range and the time. We don't keep photos. The raw text of the QR code is deleted after 30 days.

How we calculate the index

The Fair Price Index of a venue is a weighted average of the ratings from verified customers. With small samples it is pulled towards the category average, and a lower bound shows how certain we are. Every purchase is rated on the five survey questions, weighted 40/25/15/10/10. Version: fpi_v1.2.

purchase score s = 0.40·Q1 + 0.25·quality + 0.15·quantity + 0.10·transparency + 0.10·would buy again Q1 “overall value” 0–10 → 0–100; the others 1–5 → 0–100 time weight w = 0.5 ^ (age in days / 120) after 365 days: 0 account weight a = 0.4 → 1.0 by account age and variety effective sample n_eff = W² / Σ(w·a)² W = Σ w·a raw index FPI_raw = Σ w·a·s / W index FPI = (n_eff · FPI_raw + 25 · C) / (n_eff + 25) C = category average lower bound FPI_LB = FPI − 1.28 · σ_w / √n_eff “Fair Price” badge n_eff ≥ 40 and FPI_LB ≥ 80 and 60-day hold and no open report

The five measures. Overall value 40% · Quality 25% · Quantity / size 15% · Transparency 10% · Would buy again 10%. Example: 9, 4, 4, 5, 4 → 83.5.
Decay. A rating loses half of its weight in 120 days. A venue that improves sees it in the index within weeks.
Prior. A venue with 5 ratings cannot look more certain than one with 500. 25 “virtual” ratings at the category average pull small samples towards the average.
Lower bound. The badge is awarded on the lower bound, not on the point estimate. A small sample penalises itself.
New accounts. At most 20% of a venue’s weight can come from accounts younger than 30 days.
Confidence. limited below 20, good up to 49, high from 50 effective ratings.

The methodology code is open, with public test vectors, so anyone can compute the index of any venue. A review of the weights is planned after the first 5,000 ratings and will be released as a new version with an explanation.

Decay. A rating loses half its weight in 120 days. A venue that improves sees it in the index within weeks.
Prior. A venue with 5 ratings can't look more certain than one with 500. 25 “virtual” ratings at the category average pull small samples towards the average.
Lower bound. The badge is awarded on the lower bound, not on the point estimate. A small sample penalises itself.
New accounts. At most 20% of a venue's weight can come from accounts less than 30 days old.
Confidence. Limited below 20, good up to 49, high from 50 effective ratings.

The methodology code is open, with public test vectors, so anyone can calculate the index of any venue. A reassessment of the weights is planned after the first 5,000 ratings and will be released as a new version with an explanation.

What we do against manipulation

One receipt, one rating. Reuse is technically impossible.
A person can rate the same venue at most once every 30 days. Minimum receipt amount: 3 €.
We monitor the rate of ratings per venue and per fiscal device, the sequence of receipt numbers, clusters of devices and networks, and the distance at the time of scanning.
The result of a rating is not shown to the person after submission. There is nothing to trade for a reward.
No administrator, merchant or founder can set a percentage. No such field exists. Ratings can only be removed by two people, and the removal stays in the log.
Reports from customers (“Seen something unfair?”) are checked; if a problem is confirmed, the company must respond. Reports are not published and are not linked to a person.
If manipulation is proven, only the invalid ratings are dropped, the badge is removed, and the venue gets a public report and is ineligible for the badge for 12 months.

The two badges

“Rated on Chestni Ceni” — the venue is in the system and invites its customers to rate it. The first stage in the pilot. It is not a badge for a high rating.

“Fair Price” — earned: an effective sample size above 40, a lower bound above 80 for 60 days, and no active report. It can't be bought.

The QR code on the sticker always leads to the venue's current status, including when the badge is not in effect. Venues of companies connected to the founder or the team are marked on their profile, do not get the badge for the first 12 months, and their data is audited externally.

Independence: the rating is not for sale

The index measures customers' perception of value for money. It is not an assessment of the legality, reasonableness or morality of prices and cannot be used as such.
A company can't pay for a rating, a badge, a ranking or the removal of a rating. Participation in the pilot is free; later, companies pay only for analytics and software.
We don't publish individual ratings and we don't link a rating to a person. Rater profiles are pseudonymous.
We provide institutions only with aggregated public data. Data on a specific venue is provided only where required by law.
Anyone can report a rating, a venue or a practice through “Report an issue”. We respond with a reasoned decision.

This page fulfils our obligation under Art. 68e(5) and (7) of the Consumer Protection Act to disclose how we ensure that reviews come from real buyers, and which parameters determine the ranking. The full rules: participation terms, terms of use, privacy.

Methodology versions

fpi_v1.2 · September 2026 · the five measures, weighted as in the concept (40/25/15/10/10); all five questions are mandatory. Decay, prior, lower bound and the badge hold period are unchanged.
fpi_v1.1 · September 2026 · first public version: two mandatory questions (70/30), exponential decay, Bayesian prior, lower bound, badge hold period.

Every change is published here with a reason and a date, and past indexes are recalculated under both versions for comparison. How it works for customers →

Questions about the badge

What does the “Fair Price” badge mean?

Enough real customers say it was worth it: an effective sample size above 40, an index lower bound above 80 for 60 days, and no active integrity report. It can't be bought.

What does “Rated on Chestni Ceni” mean?

The venue is in the system and invites its customers to rate it. The first stage in the pilot. It is not a badge for a high rating.

Can the badge be removed?

Yes, automatically: when the lower bound falls below the threshold, when there is an active integrity report, or when manipulation is proven (in which case the venue is also ineligible for the badge for 12 months). The QR code on the sticker always leads to the live status, so a removed badge shows up straight away.

Can companies connected to the team get the badge?

Not for the first 12 months. They are marked on their profile as a related party, and their data is audited externally.

See all questions