What are the API rate limits?

Limits are per-account tiers — a bundle of four quotas. Reads (GET) and writes (POST) use separate per-minute buckets:

• Default tier: 60 reads/min, 60 writes/min, 20,000 requests/day, 100 concurrent active orders.
• $500 tier (unlocks automatically at $500 lifetime top-ups): 500 reads/min, 120 writes/min, 100,000/day, 500 concurrent.
• $1000 tier (at $1,000 lifetime top-ups): 1,000 reads/min, 200 writes/min, 300,000/day, 1,000 concurrent.
• Requests before authentication, per IP, per minute: 2,500.
• Price queries, per account: 1,000 per 5 hours and 10,000 per 7 days (VIP: 5,000 / 50,000).

Tiers unlock the moment your top-up lands — no review needed. Responses expose X-RateLimit-* and X-RateLimit-Day-* headers reflecting your personal tier — they are authoritative. After a 429, wait for Retry-After before retrying and cache catalog responses client-side.