How TierDrift turns pricing pages into durable evidence
Our first methodology version defines a narrow, auditable pipeline: public pages only, normalized offers, immutable snapshots, and no inferred change without evidence.
1. Source scope
TierDrift reads only pricing information that is publicly accessible without an account. The preferred source is the vendor’s official pricing page. We record the exact source URL and an observation timestamp in UTC.
We do not copy full marketing pages. We extract the minimum facts needed for a transformative comparison: plan name, displayed price, billing cadence, unit, a short plan description, and a small set of plan highlights.
2. Normalization contract
- Currency is stored explicitly; the initial dataset publishes USD observations.
- Amounts are stored in minor units to avoid floating-point ambiguity.
- Monthly equivalents billed annually remain labeled “annual”; TierDrift does not present them as month-to-month prices.
- Custom and contact-sales tiers are recorded as unlisted, never estimated.
- Per-user, per-member, per-seat, workspace, and organization units remain distinct.
3. Append-only history
Every accepted observation generates a timestamped normalized snapshot, a transformed source-evidence artifact, and a capture manifest that records their SHA-256 fingerprints. The archive command refuses to overwrite any existing history file, while CI rejects historical edits across the complete pull-request or push range.
A product page can therefore say “no verified changes yet” while still preserving its first observation. Once a later snapshot differs and the difference is reviewed, TierDrift will publish a change event linked to supporting evidence.
4. Derived metrics
Each indexable product record includes at least one TierDrift-only calculation. The current release uses transparent tier premiums or entry-price deltas. Every metric displays its formula and method version next to the value.
Percentage premium = (higher listed price − lower listed price) ÷ lower listed price × 100. Calculations compare prices with compatible units and billing cadence only.
5. Corrections and limitations
Pricing pages can personalize by region, currency, contract term, taxes, or account status. TierDrift’s observations are research records, not purchase quotes. If a source changes or a record is incorrect, email hello@tierdrift.com with the product, source URL, and supporting evidence.