Senior HubSpot Marketplace App Developer (Custom Channels + Workflow Extensions + Certification)
We are looking for a highly experienced HubSpot Marketplace App Developer to lead the end-to-end development, certification, and publishing of an official HubSpot App.
This is a full-scale Marketplace app build, not a basic integration. Only apply if you have proven experience shipping public HubSpot Marketplace apps — especially involving Custom Channels API and Workflow Extensions.
Project Overview
The goal is to design, develop, certify, and publish a public HubSpot Marketplace app that integrates a third-party messaging platform with HubSpot.
The app must support two integration levels:
Case 1: General Integration (Starter & Pro Users)
CRM Card (right sidebar) integration on Contact, Deal, Company, and Ticket records
Embedded iFrame chat interface per associated contact
Conversation-based display logic (phone number matching)
Real-time activity logging (inbound/outbound messages to timeline)
Two-way contact sync (name, phone, opt-in status)
Duplicate handling with one primary contact per phone number
Custom Workflow Action:
Send message template
Dynamic channel selection (real-time)
Dynamic template selection (real-time)
Placeholder handling
Native HubSpot reporting support:
Number of conversations
Templates used
Opt-ins collected
Unread conversations (per channel)
Message volume (inbound, outbound, AI agent)
Suggest the creation of new conversation if none exists
Case 2: Enterprise Integration (Service/Sales Hub Enterprise Only)
Full Custom Channels API integration
Native Inbox messaging support
Agents reply from HubSpot Inbox (messages sent via external API)
24-hour session handling logic:
Within 24h: free text allowed
Outside 24h: template selection required
UI must reflect the session status correctly
Critical Requirements
Must pass official HubSpot Marketplace certification
App must be publicly listed
Complete handover of source code and technical documentation
UX/UI must align seamlessly with HubSpot design standards
Robust error handling (including API outage handling)
All necessary technical steps required for certification are included in the scope
Required Expertise
You MUST have:
Proven experience publishing HubSpot Marketplace Apps
Deep knowledge of:
HubSpot Public Apps (OAuth, scopes, webhooks)
CRM Extensions (CRM Cards, iFrames)
Timeline Events API
Workflow Extensions API
Custom Channels API (required)
Conversations API
Experience handling Marketplace security review & certification process
Strong backend architecture experience (Node.js / TypeScript preferred)
Experience with scalable webhook and sync systems
This is senior-level work. Not suitable for junior or mid-level developers.
Deliverables
Fully functional HubSpot Marketplace app
Successful certification & approval
Public listing
Source code ownership transferred
Technical setup & maintenance documentation
Clean, well-commented codebase
Timeline
Target project start: Within 3 weeks
Completion target: Aggressive timeline — please propose a realistic delivery schedule based on experience.
When Applying, Please Include
Links to HubSpot Marketplace apps you have built
Specific experience with Custom Channels API
Experience with Workflow Extensions
Estimated timeline
Estimated fixed-price cost
Your proposed technical stack
Only apply if you have direct, production-level experience with HubSpot Marketplace apps.
We are looking for a senior, reliable partner who understands both the technical and certification complexity involved.
Apply Now
Apply Now
This is a full-scale Marketplace app build, not a basic integration. Only apply if you have proven experience shipping public HubSpot Marketplace apps — especially involving Custom Channels API and Workflow Extensions.
Project Overview
The goal is to design, develop, certify, and publish a public HubSpot Marketplace app that integrates a third-party messaging platform with HubSpot.
The app must support two integration levels:
Case 1: General Integration (Starter & Pro Users)
CRM Card (right sidebar) integration on Contact, Deal, Company, and Ticket records
Embedded iFrame chat interface per associated contact
Conversation-based display logic (phone number matching)
Real-time activity logging (inbound/outbound messages to timeline)
Two-way contact sync (name, phone, opt-in status)
Duplicate handling with one primary contact per phone number
Custom Workflow Action:
Send message template
Dynamic channel selection (real-time)
Dynamic template selection (real-time)
Placeholder handling
Native HubSpot reporting support:
Number of conversations
Templates used
Opt-ins collected
Unread conversations (per channel)
Message volume (inbound, outbound, AI agent)
Suggest the creation of new conversation if none exists
Case 2: Enterprise Integration (Service/Sales Hub Enterprise Only)
Full Custom Channels API integration
Native Inbox messaging support
Agents reply from HubSpot Inbox (messages sent via external API)
24-hour session handling logic:
Within 24h: free text allowed
Outside 24h: template selection required
UI must reflect the session status correctly
Critical Requirements
Must pass official HubSpot Marketplace certification
App must be publicly listed
Complete handover of source code and technical documentation
UX/UI must align seamlessly with HubSpot design standards
Robust error handling (including API outage handling)
All necessary technical steps required for certification are included in the scope
Required Expertise
You MUST have:
Proven experience publishing HubSpot Marketplace Apps
Deep knowledge of:
HubSpot Public Apps (OAuth, scopes, webhooks)
CRM Extensions (CRM Cards, iFrames)
Timeline Events API
Workflow Extensions API
Custom Channels API (required)
Conversations API
Experience handling Marketplace security review & certification process
Strong backend architecture experience (Node.js / TypeScript preferred)
Experience with scalable webhook and sync systems
This is senior-level work. Not suitable for junior or mid-level developers.
Deliverables
Fully functional HubSpot Marketplace app
Successful certification & approval
Public listing
Source code ownership transferred
Technical setup & maintenance documentation
Clean, well-commented codebase
Timeline
Target project start: Within 3 weeks
Completion target: Aggressive timeline — please propose a realistic delivery schedule based on experience.
When Applying, Please Include
Links to HubSpot Marketplace apps you have built
Specific experience with Custom Channels API
Experience with Workflow Extensions
Estimated timeline
Estimated fixed-price cost
Your proposed technical stack
Only apply if you have direct, production-level experience with HubSpot Marketplace apps.
We are looking for a senior, reliable partner who understands both the technical and certification complexity involved.
Apply Now
Apply Now