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: Microsoft Project
providerId: microsoft-project
created: '2026-05-04'
# Provenance stamped 2026-08-11: this artifact was written by the API Evangelist
# bulk sweep dated 2026-05-04, not harvested from the provider. See roadmap#35.
method: generated
modified: '2026-05-05'
reconciled: true
tags:
  - Rate Limiting
  - Project Management
  - Microsoft
  - SharePoint
description: Microsoft Project Online APIs are hosted on SharePoint Online, so they inherit SharePoint's
  per-user / per-tenant throttling, plus Power Platform request limits via the Microsoft 365 license
  category. Limits are enforced via 429 / 503 responses with Retry-After headers; clients must honor
  the header. There is no published per-second cap — Microsoft uses a dynamic algorithm based on resource
  consumption.
sources:
  - https://learn.microsoft.com/en-us/sharepoint/dev/general-development/how-to-avoid-getting-throttled-or-blocked-in-sharepoint-online
  - https://learn.microsoft.com/en-us/power-platform/admin/api-request-limits-allocations
headers:
  retryAfter: Retry-After
  ratelimitLimit: RateLimit-Limit
  ratelimitRemaining: RateLimit-Remaining
  ratelimitReset: RateLimit-Reset
responseCodes:
  throttled: 429
  serviceUnavailable: 503
limits:
  - name: SharePoint Online dynamic throttling
    scope: account
    metric: varies
    limit: 'Dynamic per-user / per-tenant throttling based on resource consumption; no published
      per-second cap.'
    notes: SharePoint enforces both 429 and 503 responses. Clients must read Retry-After and back off.
  - name: Power Platform requests (Microsoft 365 / Project license)
    scope: account
    metric: requests_per_day
    limit: 6000
    timeFrame: day
    notes: Project Online / Plan 1 / Plan 3 fall in the Microsoft 365 + Project Online (Plan 1, 3, 5)
      category at 6,000 PPR per user per 24 hours.
  - name: Power Platform non-licensed pool (Power Apps / Automate, Project tenant)
    scope: account
    metric: requests_per_day
    limit: 25000
    timeFrame: day
    notes: Tenant-pooled non-licensed identities (service principals, application users).
policies:
  - name: Honor Retry-After
    description: SharePoint and Project Online responses with 429 or 503 include a Retry-After header.
      Wait for the indicated number of seconds before retrying. Failure to honor results in temporary
      blocking.
  - name: Decorate user-agent
    description: Microsoft requires a meaningful User-Agent header (ISV|company|product/version) on
      CSOM and REST traffic; undecorated traffic is more aggressively throttled.
  - name: Reduce concurrency
    description: Lower the number of parallel threads / connections from a single account before
      lowering the per-second rate.
  - name: Use sandbox (test) tenants
    description: Do not load-test against production; Microsoft does not offer a higher rate for testing.
  - name: 24-hour PPR window
    description: Power Platform request entitlement is a sliding 24-hour window; limits do not roll over.
maintainers:
  - FN: Kin Lane
    email: kin@apievangelist.com