This decision matters most in HR tech, benefits, and payroll, where a single platform might need to connect to 60+ external systems, each with its own opinion on how APIs should work. Get it wrong, and you're stuck normalizing inconsistent formats for months.
This article breaks down REST vs RPC, when each makes sense, and how unified APIs like Bindbee remove the decision entirely for benefits and HR data.
TL;DR
- REST is resource-oriented (nouns, HTTP verbs); RPC is action-oriented (function calls over the network)
- Discoverability, caching, and standardization favor REST; raw speed and action-heavy workflows favor RPC
- Partner-facing SaaS APIs usually ship REST; internal service-to-service calls often use RPC or gRPC
- Picking wrong can cost months of engineering time normalizing third-party formats
- Unified APIs collapse 60+ systems' protocol differences into one consistent interface
REST vs RPC: Quick Comparison
| Dimension | REST | RPC |
|---|---|---|
| Data model | Resource-based (/employees) |
Action-based (/getEmployee) |
| Performance | Moderate, larger payloads, chatty for nested data | Faster, especially with gRPC/Protobuf |
| Discoverability | High, predictable via HTTP verbs and URLs | Low, requires documentation |
| Standardization | Loose (OpenAPI, JSON-API) | Varies (JSON-RPC, gRPC, SOAP) |
| Best fit | Public/partner APIs, many consumer types | Internal service-to-service, high-frequency jobs |
What Is REST?
REST is an architectural style built on stateless, cacheable, resource-oriented HTTP interactions. Most third-party SaaS platforms (HRIS, payroll, benefits carriers) expose REST-flavored APIs for partner integrations because it maps cleanly onto business objects like employees, benefits elections, and dependents.
Why it works for integrations:
- Predictable CRUD patterns cut onboarding time for new engineers
- HTTP caching reduces redundant calls to rate-limited third-party APIs
- A uniform interface makes it easier to build SDKs across many providers
Postman's 2025 State of the API report puts REST usage at 93% among surveyed developers , confirming REST as the default for public and partner APIs.
Not every "REST" API is pure REST. Many are "RESTish": they use HTTP verbs and JSON without fully following Fielding's original constraints (hypermedia, strict statelessness). In practice, RESTish is what you'll actually encounter.
Where REST Shows Up in HR and Benefits Integrations
Syncing employee records, benefits elections, and dependent data between an HR platform and downstream systems is a REST-shaped problem.
ADP documents RESTful resource endpoints for partner access, BambooHR calls its API a "RESTful Internet protocol," and Gusto's Embedded Payroll product uses RESTful endpoints with OAuth2. These are concrete, publicly documented examples, not proof that every endpoint on every platform is REST.
What Is RPC?
RPC means executing a remote function call over the network. Instead of "give me the employee resource," you're saying "run this operation." That model fits command-driven tasks well: triggering a payroll run, kicking off a bulk sync, processing a webhook.
Why it works for these tasks:
- Lower latency for real-time sync jobs
- Simpler mental model for action-heavy workflows
- Smaller payloads with modern implementations like gRPC/Protobuf
RPC comes in several flavors: JSON-RPC, XML-RPC, SOAP (mostly legacy at this point), and gRPC, the modern high-performance option built on Protocol Buffers and HTTP/2.
Where RPC Shows Up in Practice
Slack's own documentation describes its Web API as a collection of "HTTP RPC-style methods": a useful reminder that HTTP transport doesn't automatically mean REST. Internally, many data pipelines use gRPC for service-to-service calls when polling or pushing updates from third-party systems.
That performance edge shows up in published numbers. A Google-authored gRPC benchmark found gRPC delivered 5x–10x lower latency than a simple RESTful JSON service, up to the 95th percentile, plus meaningful bandwidth savings.
The test is from 2016, used unary calls, and compared against a simple JSON HTTP service. Treat it as a directional data point, not a guarantee for your payroll workload.
REST vs RPC: Which Is Better for Third-Party SaaS Integrations?
The right answer depends on four factors:
- Number of consumers — public/partner APIs with many client types need REST's predictability
- Discoverability needs — if third-party developers must self-serve, REST wins
- Latency requirements — high-frequency internal sync jobs favor RPC/gRPC
- How many disparate systems you're normalizing — multi-protocol vendor sprawl favors a unified abstraction layer
Quick rule of thumb:
- Choose REST if you're exposing a partner-facing API to mobile, web, or third-party developers who need cacheable, predictable endpoints
- Choose RPC if you're building internal, high-frequency sync jobs between backend services you control end-to-end
Here's the part that actually matters for integration teams: the real challenge isn't picking REST or RPC for your own API. It's that Workday exposes SOAP, REST, and RaaS; ADP and Rippling lean on SFTP for parts of their data; Gusto and BambooHR go REST-first.
Every vendor decided differently, and you have to speak all of their dialects. That is the problem Bindbee's unified API solves: it normalizes REST, SOAP, RPC-like, and file-based systems behind one consistent interface, so your team writes integration logic once instead of once per protocol.
Real-World Example: Simplifying Multi-Protocol Integrations
Benefits administration and HR tech platforms don't get to pick their vendors' protocols. Workday leans on SOAP and RaaS report configurations. ADP Workforce Now, Rippling, Paylocity, and several ben-admin platforms rely partly on SFTP file exports. Others expose REST.
Maintaining custom integration code for each variant is slow. That cost shows up clearly in customer stories. Newfront described its prior setup as "12-week HRIS integration chaos": multiple source systems, no consistent format.
What changed with a unified API:
- Bindbee's connectors handle each vendor's native protocol (REST, SOAP, RaaS, SFTP) behind the scenes
- An SFTP-to-API bridge converts CSV, XML, and fixed-width file drops into the same normalized JSON used for direct API integrations
- Applications call one consistent REST interface regardless of what's happening underneath
The results, drawn from real customer outcomes:
- Newfront went from 12 weeks of integration chaos to 48 hours
- Phin cut customer onboarding time by 76%, going live in 48 hours instead of 10+ weeks
- Healthee's employers went from two-plus months per custom integration to connecting an HRIS in minutes
- ThrivePass moved from monthly batch 834 files to real-time webhooks, shrinking onboarding from six weeks to under one week
Teams no longer need to re-argue REST vs RPC for every new vendor. The protocol question gets answered once at the infrastructure layer—Bindbee's unified API across 60+ HRIS, payroll, and carrier systems—instead of every time a new system hits the roadmap.
Conclusion
Neither REST nor RPC is universally better. REST wins when you need public-facing, discoverable, cacheable APIs. RPC wins when you're building fast, action-oriented internal services. Most real-world systems, including Workday, use both.
The real cost for SaaS integration teams was never the REST-vs-RPC decision itself. It was maintaining connections to dozens of third-party systems that each answered that question differently. That is precisely where unified API infrastructure earns its keep.
Frequently Asked Questions
Is RPC better than REST?
RPC often outperforms REST in raw speed and simplicity for action-oriented tasks. REST wins on discoverability, standardization, and long-term maintainability for public APIs.
Is REST a form of RPC?
No. REST is architecturally distinct, built around resources rather than procedures. Poorly implemented "RESTish" APIs, however, often behave like RPC with HTTP verbs bolted onto pretty URLs.
Is RPC the same as gRPC?
No. gRPC is a modern, high-performance implementation of the RPC concept using Protocol Buffers and HTTP/2. It's not identical to older RPC standards like SOAP or XML-RPC.
Which is more secure, REST or RPC?
Security depends on implementation — authentication, TLS, input validation — not the paradigm itself. REST's standardization can make security audits somewhat more straightforward.
How does a unified API handle both REST and RPC third-party systems?
Unified APIs like Bindbee maintain protocol-specific connectors for each underlying system (REST, SOAP, SFTP) and normalize the data behind one consistent interface.
Do most SaaS companies use REST or RPC for their public APIs?
REST remains dominant for public and partner-facing SaaS APIs due to its predictability. RPC and gRPC are more common for internal service-to-service communication.
