"It's like an engineer's dream tool" - Sequence replaces their existing integration stack with Integration.app


  • Replace existing unified API provider with a more flexible and customisable option
  • Save engineering time & resources on building integrations.
  • Integrate with Xero, Quickbooks, Salesforce, Hubspot & dozens of more apps very quickly in a unified way without losing depth/customisability


  • Integration.app was beyond any solution they evaluated in the market after speaking with multiple vendors
  • Sequence replaced their previous integration partner with Integration.app in just 2 weeks

Company Overview:

Founded: 2022

Industry: Billing/Fintech

Number of employees: 22

Location: London, UK

Website: https://www.sequencehq.com/


  • Sequence is a platform for streamlining pricing, billing, and invoicing workflows for fast-growing B2B SaaS companies, backed by leading VCs (A16z, Firstminute Capital, Salesforce Ventures & more)
  • It’s designed to eliminate the slowdown caused by custom pricing and ensure smooth revenue operations. They allow users to translate commercial terms from quotes or contracts into automated billing schedules, including discounts, minimums, and credit grants. It also provides a product catalog to establish a source of truth for products and pricing.
  • Sequence is on the path to becoming the leader for scaling pricing, billing and invoicing workflows and is used today by established fintech and SaaS companies like Duffel, Ravelin, Primer, Humanloop & many more.


One of the main reasons we love working with Sequence is that they are not afraid to take leaps until they find the right solution for problems they are tackling.

Sequence sits firmly within an ecosystem of payments/billing/invoicing apps and being able to access data from Accounting Systems (e.g Xero) or CRMs (e.g Salesforce) is crucial for a great customer experience. That is why connecting the apps you use as a new user is one of the most important parts of their onboarding process.

When they started building out their integration stack, they were faced with two choices: build on their own or go with a provider. They thought about hiring someone and building muscle around building integrations but recognised quickly that their expertise would’ve revolved around apps closer to home like Xero or Quickbooks. What about other types of integrations?

Chris, their Head of Engineering was initially really attracted by the idea of unified APIs:

“The promise of unified API platforms like Merge or Codat seemed very interesting, one API and you achieve your goal with a single piece of development work”.

So they decided initially to use a unified API provider to scale their integrations for Accounting & CRM tools.

Fast forward for a few months: trouble !

Sequence’s engineering team started to hit some significant roadblocks with the unified API approach:

  • They wanted real-time integrations but noticed sync lags/delays
  • Faced issues with abstraction leaking and inconsistencies across different apps. Fields in the unified API only applied to some vendors.
  • The unified API surface area kept expanding which required more custom logic on their end.
  • They decided to pull back usage of the unified APIs and just use their provider for proxy/authentication, which did not meet their goals and expectations.

This triggered a re-evaluation process of their current integration building process. Being equipped with learnings from their first attempt, they knew much better what to look for. Enter Integration.app.

Why integration.app

During their search for a solution again, Sequence found exactly what they were looking & more with Integration.app:

  • Strong unified core: it has to be consistent and reliable across SaaS apps
  • Real-time sync: fetch data from systems instantly with no delays
  • Flexibility: work around the unified integration for edge cases/custom fields in an easy way
  • Configurability: bake-in their own code, customise per customer or per SaaS app

During his evaluation process, their Head of Engineering Chris mentioned:


Implementation with Integration.app

The initial starting point for their implementation revolved around integrating with Accounting Tools (Xero, Quickbooks) and CRMs (Hubspot, Salesforce, Attio).

Sequence used a set of Actions and Flows to craft their integrations (you can read more about how both concepts work by clicking on the links).

They worked on 20+ different integration scenarios, some of them being:

  • List all the deals from multiple CRMs at once into Sequence
  • Get the companies by ID from these deals from multiple CRMs at once.
  • Implementing field mappings with a custom schema on the Sequence side and CRM side. In other words, this details how data correlates between Sequence and our universal model. Then Integration.app applies it to specific applications.
  • They also configured custom fields and customised each integration (e.g. Salesforce or Attio) separately.
  • Update an invoice in multiple accounting systems when a specific action happens in Sequence
  • Void an invoice when a specific action happens in Sequence (applied to Xero)
  • They also used our Custom UI to build a seamless experience of displaying integrations to users

What are the benefits for Sequence?

Sequence found their ideal match eventually and they are starting to see increasing benefits to their previous setups:

  • Integration speed - They were able to get integrations up and running much faster than expected.
  • Core engineering focus - Choosing Integration.app allowed all their engineers to stay focused on core product rather than building integrations from scratch as they didn’t spend time trying to figure out custom logic
  • Time to market - They can ship features faster without redoing integrations each time.

What’s next?

In the upcoming months, many more integrations are on the roadmap from sales, document management to e-signature tools.

Sequence will also prepare to experiment with Connector Builder for niche apps not currently pre-built by us.

For more details about them, feel free to check out their website: https://www.sequencehq.com/

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