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As you look to integrate applications, you might find that you need to sync non-standardâor customâfields.
For a CRM, this can be fields like âLifetime Valueâ, âSatisfaction Ratingâ, and âPreferred Contact Methodâ; for an HRIS, this can be âShift Scheduleâ, âManager Nameâ, and âPreferred First Nameâ; for an ATS, this can be âApplication Sourceâ, âExpected Salaryâ, and âTechnical Skillsââand the list goes on as you look at different types of software applications.
To help you sync custom data successfully, weâll break down the concept of a custom integration, impactful custom integrations you can implement, common challenges associated with building them, and more.
Itâs either an internal or customer-facing integration that syncs non-standard data. The integration is typically built via APIs, but it can also be implemented through other means, such as files or screen scraping.

Related: A guide to custom API integrations
Letâs break down an example of an internal custom integration and then showcase a few customer-facing use cases.
Letâs say that a candidate signs their offer letter and you need to add them to your HRIS to kickstart their onboarding.Â
With this in mind, you can integrate your ATS and HRIS, and build a flow where once a candidate is marked as âHiredâ in the former, their new profile gets created in the latter. This new profile can include all of the custom fields that are pertinent to onboarding the new hire, like their âPreferred First Name.â

Letâs imagine that you offer a CRM system. To help your customers kickstart the invoicing process seamlessly whenever an opportunity is marked as âClosed-wonâ in your solution, you can build the following integration:
Once an opportunity is changed to âClosed-wonâ in your platform, the clientâs account gets created in your customerâs ERP system. This can include syncing custom fields that help your customerâs finance team invoice the client appropriately, such as âPayment Methodâ and âDiscount Percentage.â

Related: Common two-way syncs
Custom integrations offer a variety of critical business benefits. Here are just a few worth considering for both internal and customer-facing scenarios.
Your customers likely operate differently, leading the data they collect and the ways in which they use their data to be inherently unique to their business.
By offering custom, customer-facing integrations, you can let customers sync and build flows with whatever types of data are important to their business, enabling you to meet them where they are.
Through custom, internal integrations, you can provide your teams with the data they need to make smarter decisions. This can take the form of arming reps with more personalized data on leads, providing finance with more comprehensive billing information, sharing additional insights on support tickets for customer success, etc.
Given the previous benefit, itâs perhaps little surprise that custom integrations can help you improve key business metrics, from your close rate to your retention rate.Â
For instance, by providing reps with personalized data on leads, they can respond to leads faster and with more relevant messages, helping them get more responses and, eventually, convert more prospects into clients. And, by helping customer success access more details on support tickets, they can troubleshoot issues faster and and more successfully.
Related: The benefits of API integrations
Unfortunately, custom integrations arenât necessarily easy to build and maintain. Here are some of the top challenges to be aware of.
The process of mapping custom fields in one application with fields in another can prove difficult.Â
You might, for instance, not find similar fields in the other application, forcing you to add new ones.Â
Moreover, the process of determining the best field mappings can require cross-functional alignment; the teams that use these systems and rely on this custom data will need to know how, exactly, the mappings will work and should be bought into your proposals. Otherwise, the data can be less actionable and valuable for these stakeholders.
Depending on the API provider, you might only be able to access and sync standard fields.Â
You can, potentially, turn to other integration methods to sync custom data instead, but alternative approaches come with other notable drawbacks. For instance, file-based integrations fail to sync data in, or near, real-time; while UI-based integrations (i.e., screen scraping) can easily break whenever thereâs a small change to an applicationâs UI.Â
In order to sync custom data, your engineers will need to implement data transformation logic.
This logic is often time and resource-intensive to set up and maintain, especially if you need to build several custom integrations over time. As a result, this work can pull your engineers away from the projects theyâre uniquely qualified to take on and that drives meaningful impact for your business.
Related: The challenges of building and maintaining integrations
If youâre looking to outsource your customer-facing integrations and need to build unique integrations for different customers, you can use Mergeâthe leading unified API solution.
Through Merge, you can use Field Mapping to add and sync additional fields to our Common Models; Remote Data to access and sync custom fields in the original format they appear in in the 3rd-party application; Authenticated Passthrough Request to make API requests to endpoints that let you access custom dataâand more.

Learn more about using Merge to build custom integrations by scheduling a demo with one of our integration experts.
In case you have any more questions on custom integration, weâve addressed several additional ones below.
Standard integrations sync common data types that are typically provided by SaaS applications out of the box; while custom integrations sync data types that you or your customers add to the connected SaaS applications.
Out-of-the-box integrations allow you to build integrations faster by letting you access prebuilt functionality, such as specific transformations, authentication protocols, and triggers and actions. Custom integrations, on the other hand, need to be built from the ground up.
A custom API is built to accommodate a specific set of API consumers, while a standard API lets a broad range of consumers access and interact with its endpoints.