OpenPhone API
OpenPhone (now Quo) documents a public REST API at api.openphone.com, included on all paid plans with self-serve keys. Resources cover calls, messages, contacts, and webhooks (beta) with signature verification. A hard 10 requests per second per key and no bulk export constrain backfills.
Frequently asked questions
OpenPhone scores B on the API Report Card. OpenPhone (now Quo) documents a public REST API at api.openphone.com, included on all paid plans with self-serve keys. Resources cover calls, messages, contacts, and webhooks (beta) with signature verification. A hard 10 requests per second per key and no bulk export constrain backfills.
OpenPhone has a workable official integration path. Most engineering teams can build against it directly. Solid API with minor gaps
OpenPhone (rebranded as Quo in late 2025 / 2026) is a cloud-based business phone system and AI-powered customer-communications platform built for small and growing businesses.
Vertical: VoIP / business phone system for SMBs (horizontal SaaS, not industry-specific). Small-business owners, sales reps, support agents, recruiters, and operators log in via web, desktop (macOS/Windows/Linux), or mobile (iOS/Android) apps and make/receive calls, send SMS/MMS, listen to voicemails, and work shared inboxes where the whole team sees one threaded conversation per contact.
OpenPhone/Quo is one of the most recognized modern SMB business phone brands, powering 90,000+ businesses including Farmers Insurance, Supabase, Keller Williams, and the Chicago Bears.
Yes, for any small business that runs its customer communications on OpenPhone/Quo, it is the system of record for the full conversational dataset: every inbound and outbound call with recording and AI transcript, AI call summaries, AI call tags, SMS/MMS thread history (often the primary customer-comms channel), voicemails, shared inbox threads with internal comments, Sona AI receptionist transcripts and booked actions, contact records with custom fields, conversation dispositions and notes synced to HubSpot/Salesforce/Pipedrive/Gong, ported phone-number inventory, and call/SMS billing/usage data.
Founded 2018 by Mahyar Raissi and Daryna Kulya, graduated Y Combinator (W19), and based in San Francisco and Toronto.
Hard rate limit of 10 requests/second per API key with 429 on overage, tight for any high-volume export, bulk contact sync, or backfill job. Contact custom field definitions are read-only via API, you can read them and set values on contacts, but you cannot create or edit custom fields programmatically; must use the in-app UI. Full sourced list under Sources below.
Common alternatives include RingCentral, Zoom Phone, Dialpad, 8x8, Nextiva, Aircall. Graded alternatives appear under "More from the report card" below.
Grades measure one thing: can a customer's engineering team get their own data out programmatically? We check six things (whether a real API exists, how access is gated, data coverage, auth quality, docs and developer experience, and stability) and roll them into a letter grade. Grades get re-verified, and they only move on evidence.