How Cart2Save Rankings Work
Last updated: May 2026 · Algorithm version v2.0
Our Commitment
Cart2Save exists to help you pay less. We never accept payment to rank a product higher. Every ranking decision is auditable and governed by ten constitutional invariants.
Effective Price
We rank by effective price — not list price. Effective price is what you actually pay after cashback:
- base_price — the listed price at the merchant
- commission_rate — what the merchant pays us when you buy
- reliability — how fresh and verified that commission data is (0–1)
- 0.5 — we pass half the commission back to you as cashback
Confidence Score
Every result shows a confidence score (0–100) built from four factors:
How recently the price was fetched
Did we get a live API response?
Has the price been consistent?
How fresh is the commission data?
What We Never Do
- Accept payment to rank a product higher
- Show a result without logging an evidence record
- Use personal data for ranking
- Change rankings based on merchant pressure
- Claim a price is verified when it isn't
Evidence Trail
Every comparison page generates an evidence record before results are returned. Each record contains the ranking algorithm version, which sources were queried, what results were shown in what order, and a constitutional assertion that no paid placement occurred. Evidence records are immutable once written.
Ten Constitutional Invariants
- Ranking always by effective price ascending
- Cashback computed from verified commission data only
- Evidence record written before every comparison result
- No paid placement under any circumstance
- Commission confidence decays over time — stale data is disclosed
- Every redirect is logged before firing
- Cashback state machine: pending → confirmed → paid (no shortcuts)
- Price history append-only — no retroactive edits
- User data never used for ranking
- Algorithm version pinned per evidence record