Solvent API v2 — General Availability

Solvent API v2 is now generally available.

When we started designing v2, the question we kept coming back to was: what would this API look like if we built it knowing everything we know now about how our customers actually use it? The answer required more changes than a minor version bump could accommodate. So we built v2 from the ground up, carrying forward the parts that worked and rethinking the parts that did not.

What Changed

The most significant change is the unified API surface. In v1, payments, accounts, and FX were separate API products with separate authentication flows and separate base URLs. In v2, everything is accessible through a single endpoint with a single API key.

Javascript

# v1 — three separate base URLs
curl https://payments.Solvent.com/v1/payments
curl https://accounts.Solvent.com/v1/accounts
curl https://fx.Solvent.com/v1/rates
 
# v2 — one unified base URL
curl https://api.Solvent.com/v2/payments
curl https://api.Solvent.com/v2/accounts
curl https://api.Solvent.com/v2/fx/rates

Idempotency keys are now supported on all write endpoints. This was one of the most requested features from customers building payment workflows where duplicate requests needed to be handled gracefully.

Javascript

curl -X POST https://api.Solvent.com/v2/payments \
  -H "Authorization: Bearer YOUR_API_KEY" \
  -H "Idempotency-Key: pay_request_01jk9m" \
  -H "Content-Type: application/json" \
  -d '{"amount": 10000, "currency": "GBP", "destination": "acc_01jk4p"}'

SDK Availability

Official SDKs for Node.js, Python, and Go are available today.

Javascript

# Node.js
npm install @Solvent/sdk
 
# Python
pip install Solvent-sdk
 
# Go
go get github.com/Solvent-finance/Solvent-go

Full SDK documentation is at docs.Solvent.com/sdks.

v1 Deprecation Timeline

The v1 API will continue to receive security patches until March 31, 2026, at which point it will be retired. No new features will be added to v1. The migration guide covers every breaking change and provides side-by-side examples for each endpoint.

New Features

Unified API surface — Payments, accounts, FX, and reporting are now accessible through a single versioned API. The v1 API remains supported until March 2026.
Idempotency keys on all write endpoints — Every POST endpoint now accepts an Idempotency-Key header. Duplicate requests with the same key return the original response without creating a duplicate resource.
Cursor-based pagination — All list endpoints now support cursor-based pagination via the after and before parameters. Page-based pagination is deprecated and will be removed in v3.
Webhook signing — All webhook payloads are now signed with an HMAC-SHA256 signature. Verification instructions are in the webhook security guide.
SDKs for Node.js, Python, and Go — Official SDKs are now available. Install via your package manager and find the full reference at docs.Solvent.com/sdks.

Improvements

Improved error messages — All 4xx error responses now include a message field with a plain-English explanation and a docs_url field linking to the relevant section of the API reference.
Expanded test mode — The test environment now supports simulated payment failures, FX rate overrides, and configurable settlement delays. Full details in the test mode guide.
Rate limit increases — Default rate limits have been increased from 100 requests per minute to 500 requests per minute for all plans.

Fixes

Fixed: Rate limit headers missing on 429 responses — The X-RateLimit-Remaining and X-RateLimit-Reset headers were not being returned on rate limit errors. This has been corrected across all endpoints.
Fixed: Timestamp precision on transaction records — Transaction timestamps were being returned with second-level precision in some responses and millisecond precision in others. All timestamps now return in ISO 8601 format with millisecond precision.