Docs

Rate limits and caching

The API is free and deliberately small. It runs on the same Worker as the website, so the limits are strict.

Limits

Limit	Value	Applies to
Per client	about 15 requests per minute	each client address
Shared ceiling	about 600 requests per minute	all API users together, per Cloudflare location
Freshness	data changes once an hour	every endpoint

The count is kept per Cloudflare location and is eventually consistent, so a short burst can get through before the limit applies. Stay at or below the stated rate; do not rely on the burst.

When you hit the limit

You get 429 and a Retry-After header in seconds (60). Wait that long. The check runs before any data is read, so a refused request costs the site almost nothing. Clients that keep going, or that spread requests over many addresses to avoid the limit, may be blocked.

Response

HTTP/2 429
retry-after: 60
content-type: application/json; charset=utf-8

{ "error": "Rate limit reached. Wait a minute and slow down; see the limits in the docs.", "docs": "https://peptilyze.com/docs/api/" }

Caching and ETags

Successful answers send Cache-Control: public, max-age=300 and a weak ETag that changes with each hourly snapshot. Send it back in If-None-Match and you get an empty 304 while nothing changed.

Conditional request

# First request: note the ETag
curl -si https://peptilyze.com/api/v1/market | grep -i '^etag'
# etag: W/"api-1794229474408-9cbeac4629e69cf20b44b8b7bcaa20db"

# Later: ask only for changes. 304 means nothing changed.
curl -si -H 'If-None-Match: W/"api-1794229474408-9cbeac4629e69cf20b44b8b7bcaa20db"' \
  https://peptilyze.com/api/v1/market | head -1
# HTTP/2 304

Being a good client

Fetch /api/v1/compounds or /api/v1/shops once and cache it; they cover the whole catalog in one request.
Poll no more often than every few minutes. The numbers only change hourly (the sync runs at the top of the hour).
Send a User-Agent that names your application.
Need more than this allows, for example a daily file? Say so through the form (choose “Something else”).