Dan Stillgoe
June 01, 2026
A standard HubSpot implementation is one thing. Connecting HubSpot to an ERP, dealer management system, data warehouse, or proprietary internal platform is something else entirely. This list covers 10 agencies that have earned HubSpot's Custom Integration Accreditation, evaluated on the same criteria so you can compare what actually matters for your situation.
This list was last updated June 2026. The five criteria below drove every inclusion and exclusion decision.
Blend is a B2B HubSpot agency specializing in complex implementations that connect HubSpot to the systems running the rest of the business. Their integration work spans ERP connections, dealer management platforms, product configurators, and automated data pipelines for mid-market companies in manufacturing, logistics, and professional services. With over a decade delivering technically demanding HubSpot projects for US and UK clients, Blend combines the engineering depth needed for custom integration with the commercial understanding needed to build something the whole organization actually uses.
Proof: Blend has delivered technically complex HubSpot integrations for B2B companies across manufacturing and logistics, including:
Aptitude 8 is a technical HubSpot consulting firm with the largest technical consulting team of any HubSpot partner. They specialize in implementing, integrating, and extending HubSpot for enterprise organizations where standard configuration is not sufficient. Their work covers custom objects, coded workflows, and integrations connecting HubSpot to ERPs, financial platforms, data warehouses, and internal tools. Clients include Uber Freight, SXSW, and Formstack, and their accreditations cover CRM Implementation, Custom Integrations, and Advanced CMS.
Struto is an Elite HubSpot Solutions Partner and systems integrator that develops and deploys its own middleware platform, StrutoCORE, to connect HubSpot to business systems including SAP, Sage, Microsoft Dynamics, and custom applications. Their integration approach is built around ISO 27001-compliant infrastructure and a structured outcomes-focused roadmap, with dedicated connectors for ERP and finance systems alongside the ability to build bespoke integrations for non-standard platforms. For organizations where security, compliance, and data governance sit alongside the integration requirement, Struto brings both the technical capability and the process to match.
BBD Boom is a UK-based Elite HubSpot partner that holds all six of HubSpot's advanced accreditations, including Custom Integrations and Data Migration. They specialize in CRM implementation and migration projects for B2B companies across the UK and Europe, with a particular focus on replacing legacy CRM systems and connecting HubSpot to existing tech stacks. Their approach combines technical configuration with a strong emphasis on sales team adoption, building systems that commercial teams can operate independently after handover.
BabelQuest is a UK Elite HubSpot partner delivering strategy, technology, and ongoing services across sales, marketing, and customer service. Their methodology-led approach starts with process design before platform configuration, ensuring integrations are built to support how the business actually operates rather than replicating legacy workflows in a new system. Recognized through multiple HubSpot Impact Awards and B2B Marketing Awards, they work primarily with UK mid-market businesses and bring a consultative depth that extends beyond technical delivery into revenue operations alignment.
RevPartners is an Elite HubSpot partner built specifically around RevOps and technical CRM delivery. They hold the Custom Integration Accreditation and position their integration capability as part of a broader RevOps architecture, connecting HubSpot to Salesforce, Zendesk, Marketo, and custom platforms to create a single, clean source of truth across the revenue tech stack. RevPartners holds the distinction of being the only agency to hold Elite Accreditations with both HubSpot and Clay, and was the fastest HubSpot partner to reach Platinum, Diamond, and Elite status.
SmartBug is HubSpot's largest Elite partner and the only partner to hold all six of HubSpot's advanced accreditations, including Custom Integration and CRM Implementation. Their 2025 North American Partner of the Year win reflects a track record of delivering technically complex HubSpot programs across the full customer lifecycle, from marketing automation and CRM to eCommerce and custom system integration. They serve enterprise clients across manufacturing, healthcare, SaaS, and professional services, with the team depth and accreditation coverage to handle the most demanding integration scopes.
Salted Stone has been a HubSpot-focused agency since 2012 and specializes in enterprise implementations requiring custom API development, compliance architecture, and technical depth beyond standard onboarding. Their work spans SaaS, healthcare, and fintech, sectors where data governance requirements are non-negotiable and integrations must meet HIPAA or GDPR standards. They bring extensive API development capability and a track record of technically complex builds for clients operating in regulated environments.
Instrumental Group is an Elite HubSpot partner operating internationally with offices in Colorado and Mexico and more than 130 employees across five countries. Formed from the merger of Revenue River and Hint, two established HubSpot agencies, they combine US and Latin American market expertise with technical implementation depth across all HubSpot hubs. In addition to custom integration services, they develop proprietary HubSpot apps that extend platform functionality for clients with requirements that go beyond standard configuration, and hold all advanced HubSpot accreditations including Custom Integrations.
Blue Frog is the North American arm of Avidly, HubSpot's five-time Global Partner of the Year. As an Elite HubSpot partner with the Custom Integration Accreditation, Blue Frog delivers CRM implementation, system integrations, and revenue operations strategy for US businesses, backed by Avidly's global infrastructure and delivery capability. Their integration work includes custom portal development on HubSpot CMS connected to platforms such as ConnectWise, and they bring the process rigor of a globally recognized HubSpot organization to North American engagements.
Answer these before reaching out to any agency on this list:
If your answers point toward complex, real-time connections to ERPs or production systems with a full CRM build alongside, Blend and Aptitude 8 are worth shortlisting first. If compliance is a hard requirement, Salted Stone and SmartBug have the deepest experience in regulated environments. For UK and European projects, BBD Boom, BabelQuest, and Struto are natural starting points.
Start with the systems that need to connect to HubSpot, not the agency you want to work with. Document what data needs to flow in each direction, how frequently it needs to sync, and what happens if the integration fails. The more precisely you can describe the integration requirement, the more accurately any agency can scope the work, and the fewer surprises will appear once the build is underway.
Not all HubSpot integrations are the same. A native HubSpot connector requires no custom development. An iPaaS tool such as Make or Zapier can handle many common use cases. A fully custom integration built against an API is a different engagement entirely. Confirm which category your requirement falls into before evaluating agencies, because the skills and experience needed are different in each case. The agencies on this list specialize in the third category.
The best integration partners can describe a specific system they have connected to HubSpot, the challenge that made it non-standard, and the outcome. If an agency references only marketing or website work when you ask about integration experience, that tells you something. Ask directly: have you connected HubSpot to a system like ours, and can you show us what that project looked like?
Custom integrations require ongoing maintenance. APIs change, data volumes grow, and business processes evolve. Before engaging any partner, understand how they handle post-launch support, how integrations are documented for future maintainability, and what happens when the integration breaks at 2am on a Friday. The best partners build integrations that are maintainable by someone other than the person who built them.
It depends on the scope and geography of the project. For complex B2B integrations connecting HubSpot to ERPs and operational systems, Blend and Aptitude 8 are the strongest options. For enterprise integrations in regulated industries, Salted Stone and SmartBug bring the deepest compliance experience. For UK and European projects, BBD Boom, Struto, and BabelQuest have the most relevant track records. All 10 agencies on this list hold HubSpot's Custom Integration Accreditation.
Costs vary significantly based on the systems involved and the complexity of the data model. Simpler iPaaS-based integrations can be scoped from $5,000 to $15,000. Fully custom integrations built against proprietary APIs typically run $20,000 to $60,000 depending on the number of objects, sync frequency, and error-handling requirements. Enterprise integrations involving multiple systems, compliance requirements, or real-time synchronization can extend beyond that range. Always ask for a scoping engagement before agreeing to a fixed price.
A straightforward integration between HubSpot and a well-documented API typically takes four to eight weeks from scoping to deployment. More complex integrations involving proprietary systems, real-time bidirectional sync, or compliance requirements can take 12 to 20 weeks. Integrations that form part of a larger CRM implementation will run to the timeline of the broader project. Request a detailed project plan during scoping so there are no surprises once work begins.
Look for the name of the system being integrated, a description of why a custom build was needed rather than a native connector, and a measurable outcome tied to the integration itself. Good integration case studies describe what changed operationally: time saved, manual processes eliminated, data errors reduced. Be cautious of case studies that describe the build without explaining the problem it solved or the impact it had.
Every successful integration starts with a well-scoped brief and a partner who has solved a similar problem before. If your requirement involves connecting HubSpot to an ERP, inventory system, or proprietary platform, it is worth understanding how a technically grounded implementation actually works in practice. Blend's CPL case study and Kriete Truck Centers case study are two places to start.
1 June 2026
1 June 2026