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zaref / docs / zaronia-api

ZARONIA rate API

ZARONIA, the South African Rand Overnight Index Average, is the SARB benchmark designated to replace JIBAR. New contracts may no longer reference JIBAR since 1 May 2026 and JIBAR publishes for the last time on 31 December 2026.

zaref tracks the daily published rate, verified against the SARB API each day, and accumulates the history that /calc/zaronia-interest compounds over (ACT/365, compounded in arrears). Coverage is honest: requests before tracked history return an explicit earliest_available rather than a fabricated backfill.

Series

GET /v1/zaronia

SARB's ZARONIA risk-free overnight benchmark, the designated JIBAR successor (JIBAR ceases 2026-12-31), with the transition timeline and daily-rate history for compounded interest calculations.

$0.005 per call · updates: daily (SA business days, ~10:00 SAST) · effective 2026-07-14 · history at /v1/zaronia/history ($0.01)

Calculators

GET /calc/zaronia-interest

Compound-in-arrears interest on a principal over a date range, using zaref's accumulating daily ZARONIA history (ACT/365). Coverage limited to dates zaref has tracked.

Parameters: principal, start, end

$0.01 per call · example: /calc/zaronia-interest?principal=1000000&start=2026-07-10&end=2026-07-14

How agents pay

No account, no API key. Paid endpoints reply HTTP 402 with exact payment requirements; an x402 client pays USDC on Base (about two seconds to settle) and retries automatically. Invalid input is rejected free with a 400 before any payment is challenged. See the x402 quickstart.

Questions

What replaces JIBAR in South Africa?
ZARONIA. The Market Practitioners Group designated it as the successor benchmark; new JIBAR referencing stopped on 1 May 2026 and JIBAR ceases after 31 December 2026.
How is compound interest over ZARONIA calculated?
GET /calc/zaronia-interest compounds the daily rates in arrears over your date range on an ACT/365 basis, using zaref's accumulated daily history, and returns the day count and rates used.
How current is the rate?
The SARB publishes each business day and zaref verifies against the SARB API twice daily, with a public staleness flag if publication is ever missed.

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