HubSpot Developer Platform Fit — Key Sources (2026)

Angle: where the CLI sits relative to private apps, CRM API v3, custom-coded workflow actions, Operations Hub, and webhooks.

Official HubSpot docs

• Developer platform overview: https://developers.hubspot.com/docs/apps/developer-platform/overview
• Developer projects CLI reference (BETA): https://developers.hubspot.com/docs/platform/project-cli-commands
• Custom code actions (Automation API): https://developers.hubspot.com/docs/reference/api/automation/custom-code-actions
• Custom workflow actions guide: https://developers.hubspot.com/docs/guides/api/automation/custom-workflow-actions
• Legacy private apps overview: https://developers.hubspot.com/docs/apps/legacy-apps/private-apps/overview
• Service Keys (right credential for data integrations): https://developers.hubspot.com/blog/hubspot-service-keys-the-right-api-credential-for-data-integrations
• Navigating Serverless Functions on the new Developer Platform: https://developers.hubspot.com/blog/navigating-serverless-functions-on-hubspots-new-developer-platform
• Spring 2026 Spotlight (platform changes): https://developers.hubspot.com/changelog/spring-2026-spotlight
• Planning Your Migration on the HubSpot Developer Platform: https://developers.hubspot.com/blog/developer-platform-migration-timeline

Key facts (2026)

• Apps run on developer platform versions v2025.2 or v2026.03, created/deployed via the HubSpot CLI (Projects framework = code + config + assets).
• API moving to date-based versioning: /crm/objects/2026-03/contacts replaces /crm/v3/.
• Webhook subscriptions require a PUBLIC app — NOT available on private apps.
• Custom code actions require Operations Hub Pro/Enterprise; run on HubSpot-managed AWS Lambda (Node.js 16.x+ or Python 3.9 beta). Limits: 128 MB memory, 50 properties, 65,000 char string output.
• Serverless functions (App Functions) reintroduced to Projects in v2026.03 (released March 30, 2026); expose public HTTP endpoints for webhooks/public APIs.
• Service Keys: new simplified API credential admins can create without a developer; modern replacement for legacy private apps.
• OAuth v3 endpoints now date-versioned (POST /oauth/2026-03/token); required for new/recertifying marketplace apps.
• Legacy public app creation disabled for accounts created before May 26, 2026 — new marketplace apps must use Projects + CLI.