specification: API Commons Rate Limits
specificationVersion: '0.1'
schema: https://raw.githubusercontent.com/api-evangelist/interface-research/main/schema/api-commons.yml#/$defs/RateLimits
provider: FIS
providerId: fis
generated: '2026-09-10'
method: probed
source: https://docs.railz.ai/reference/errors + observed response headers on https://api.railz.ai/v2/connections
created: '2026-05-04'
modified: '2026-09-10'
limit_count: 0
tags:
- Banking
- Financial Services
- Payments
- Rate Limiting
description: >-
  FIS publishes no numeric rate limit for any of its APIs, and the one live public API emits no
  rate-limit headers. An agent calling FIS Accounting Data as a Service has no way to know how
  much budget it has left; it can only discover exhaustion by taking a 429.
limits: []
response_codes:
  throttled: 429
  service_unavailable: 503
headers:
  observed: []
  note: >-
    An unauthenticated GET to https://api.railz.ai/v2/connections on 2026-09-10 returned 401
    with a full security-header set (HSTS, CSP, X-Content-Type-Options, Referrer-Policy) and NO
    RateLimit-* , X-RateLimit-* or Retry-After header of any kind. The docs likewise document
    429 without naming a header, a threshold, a window, or a reset field.
documented_guidance:
- source: https://docs.railz.ai/reference/errors
  detail: >-
    429 is listed as one of fifteen documented status codes, with the guidance "We recommend an
    exponential backoff of your requests." No threshold and no reset signal accompanies it.
policies:
- name: Backoff
  description: Exponential backoff on 429, per the provider's own wording. Retry-After is not emitted, so the interval is the client's guess.
undocumented_products:
- name: FIS Code Connect
  note: Throughput is provisioned per financial institution at onboarding under the master service agreement; no public number exists.
evidence:
- url: https://api.railz.ai/v2/connections
  status: 401
  detail: No rate-limit header present in the response.
- url: https://docs.railz.ai/reference/errors
  status: 200
  detail: 429 documented; no limit, window, or header named.