Methodology and Calculation
Sources, calculation basis, and update policy for the rates yensend.jp displays
1. Data Source
Provider remittance quotes shown on this site are retrieved from the Wise public comparison API (/v4/comparisons/). This API is publicly accessible without authentication (source: docs.wise.com). It returns rates, fees, receive amounts, and delivery times for providers aggregated by Wise. For Taiwan TWD, yensend additionally uses the Bank of Taiwan official JPY/TWD spot buy/sell midpoint as the mid-market reference baseline.
2. Total Cost Formula
Total cost = send amount − (receive amount ÷ mid-market reference rate). This single number expresses the actual yen lost to fees and FX margin combined. Most corridors use the explicit mid-market row returned by Wise where `isConsideredMidMarketRate: true`. Taiwan TWD uses the Bank of Taiwan official JPY/TWD spot buy/sell midpoint because Wise may omit its own mid-market row on that lane.
3. Freshness Gate (30-Minute Rule)
Each provider row shows Wise's collection timestamp (dateCollected). Data older than 30 minutes may remain visible, but it is labeled "Data delayed" and is not treated as current (Japan Act against Unjustifiable Premiums and Misleading Representations Article 5(1), preventing misleading-superiority claims / internal policy F-039). Missing, NaN, or excessively old timestamps are excluded.
4. Cache Policy
To avoid overloading the Wise API, responses are cached via Upstash Redis using a Stale-While-Revalidate (SWR) pattern. The three-tier configuration is fresh 60 s / stale 180 s / Redis hard TTL 300 s, with stale responses served immediately while a background refresh runs. Single-flight locking via Redis SETNX prevents stampedes. The "cache · NN s" / "stale · NN s" badge at the top of the page surfaces the current cache state.
5. Ranking Criteria
Providers are sorted by total cost (fee + FX margin combined) ascending. Ties are broken by provider name ascending (partner-neutral D-026). Partner versus non-partner status does not affect ranking. The first-place provider receives a "Rank 1" badge, but this reflects only the result at the current display moment and does not guarantee rankings at future times, other amounts, or other corridors.
6. Advertising and Affiliate Fees
This site is a comparison information service. We may receive referral fees from some providers, but they do not influence display order or content (D-026 partner-neutral ranking). Providers with active partnership are marked with a "Partner" label inline for transparency. This site is not a fund-transfer operator and does not handle remittance services (Payment Services Act Article 2 §5).
7. Limitations
(a) Only the JPY → PHP corridor has Lane A measured verification data (2026-04-17, fact-registry F-001), which displays as a "Verified" label on the Wise row. VND / KRW / NPR / CNY / Taiwan TWD provider quotes rely on timestamped data via the Wise public API or Wise official pages without provider-native independent verification; the CNY route gate is recorded as fact-registry F-070. For Taiwan, provider quote availability is recorded as F-072 and the independent Bank of Taiwan reference midpoint as F-073. (b) Displayed provider rates are Wise-aggregated values and may differ slightly from each provider's official site. Always confirm at the provider's site before sending. (c) Delivery times are Wise-recorded estimates and vary based on FX, receiving bank hours, and remittance channel.
8. Sources and Reference Documents
Wise API documentation: docs.wise.com / Wise public comparison API: api.wise.com/v4/comparisons/ / Internal fact-registry: scripts/fact_registry.json (F-001 onward cumulative entries; see scripts/fact_registry.json for the current count) / Lane A measurement log: domain_knowledge/24_wise_api_lane_a_results.md. GitHub: github.com/dongmin7208/remittance-compare (private).