Why are IAAS platforms different from Recruitment companies?

-By Lalitha Varshini

What sets IAAS platforms and recruitment companies apart: Hiring has split into many specialized activities. They include sourcing, screening, interviewing, assessment, offer negotiation, and onboarding. Different providers have evolved to own or outsource other parts of that lifecycle. Two models that often get compared are Interview-as-a-Service (IaaS) platforms and the more traditional recruitment companies, including Recruitment Process Outsourcing providers and staffing agencies. At the surface level, both help companies hire. Under the hood, however, they differ in purpose, scope, value propositions, pricing, and technology.

What sets IAAS platforms and recruitment companies apart?

Surveys show many enterprises increasingly outsource technology and HR processes to focus on core functions, and companies that outsource HR functions report meaningful cost savings in many studies. These macro trends create fertile ground for both interview as a service vendors. So what sets Interview as a service platforms and Recruitment companies apart? Below is the comparison of both of them across seven dimensions, so firms can understand the advantages of interview as a service model for tech hiring and where each model fits in a modern hiring ecosystem. 

On the basis of the core offering and scope

1. IaaS (Interview as a Service) platforms run interviews that are usually technical or role-specific by providing trained interviewers, structured interview guides and scoring, and often integrated interview platforms like video, code editors or tasks. The focus is assessment and not sourcing or full-cycle hiring. This is why many IaaS offerings are used by engineering teams that want rigorous, consistent technical interviews without pulling internal engineers off product work. 
2. Recruitment companies own parts or all of the recruitment process from sourcing candidates, employer branding, screening, scheduling, offer negotiation, compliance, payroll for contract staffing to onboarding too sometimes. They are full-funnel partners that manage scale, relationships, and often act as an extension of HR. Market research treats RPO as a broader, higher-touch market than the narrow IaaS niche.

On the basis of skill specialization vs end-to-end capability

1. Interview as a service providers often curate panels of experienced domain interviewers which may include senior engineers along with subject matter experts who are trained in structured interviewing and rubrics. That makes Interview as a Service ideal for technical roles where interview quality and unbiased scoring matter. They pair human expertise with tech interview platforms.
2. Recruitment companies emphasize sourcing networks, relationship management, and hiring operations. Their interviewers sometimes are typically generalist recruiters or sourcers; deep technical interviewing is often subcontracted or coordinated with the client’s hiring managers.

On the basis of technology integration

1. Interview as a service vendors bundle or integrate with technical interview platforms such as live coding, automated scoring or proctoring and analytics that measure interviewer consistency and candidate signals. The technical-interview platform market itself is growing rapidly as companies digitize assessment workflows; industry reports put the 2024 market in the hundreds of millions, with multi-year double-digit CAGRs. This growth fuels more feature-rich interview as a service offerings.
2. Recruitment companies may use an ATS and analytics but are less likely to own the technical interview tooling. Their value is operational in nature such as candidate pipelines, employer brand and human networks.

On the basis of cost drives

1. Interview as a service pricing tends to be usage-based which could be per interview, per candidate assessed, or subscription tiers based on volume. Because it’s narrowly scoped, interview as a service platforms can be cost-efficient for companies that already have sourcing and onboarding in place but need interview bandwidth and quality.
2. Recruitment companies charge in diverse ways: contingent fees like percentage of first-year salary, retained search fees, hourly RPO fees, or project-based pricing. RPO engagements are often multi-year and priced to cover full lifecycle services and infrastructure.

On the basis of speed, scale and operational fit

1. Interview as a service platform scales horizontally for volume interviews. For example, mass campus hiring or multi-round technical screens by supplying many interviewers and standardized rubrics. The technical interview platform market and adoption trends show organizations are buying tools to scale technical hiring.
2. Recruitment companies scale vertically. They expand downstream services like offer management, compliance and upstream such as sourcing and typically embed within an organization’s talent function.

Further Reads: How Interview as a Service (IaaS) Enhances Recruiting Efficiency

On the basis of quality control and bias mitigation

1. Interview as a service platform often emphasizes standardized interview rubrics, interviewer training, and recorded interviews for auditability. Because their product is assessment, many such players focus on reducing interviewer variance and bias through calibration, which is increasingly important to enterprise hiring governance.
2. Recruitment companies emphasize candidate experience and conversion metrics such as sourcing yield or offer acceptance. Some RPOs also provide structured interviewing, but this is an add-on rather than the core product.

On the basis of practical guidance

1. Interview as a service platforms are more viable when the firm’s biggest bottleneck is technical interviewing or when the firm already has sourcing but is in need of assessment scale. Moreover, interview as a service platforms can also be used when firms need specialized tech interview solutions integrated with code editors and recorded sessions.
2. Recruitment companies are more viable when firms want outsourcing that covers sourcing, screening, compliance, payroll, and onboarding or when they are hiring across many functions and geographies and need a partner to own the whole recruitment process.

In conclusion, both Interview-as-a-Service platforms and recruitment companies play distinct yet important roles. Recruitment firms continue to be valuable partners for organizations that need broad, end-to-end ownership of the recruitment process, especially when sourcing large talent pools or managing complex hiring operations across geographies. Their strength lies in relationship building, pipeline management, and holistic hiring support.

Further Reads: How IaaS Can Help You Hire Smarter and Faster

However, as organizations increasingly prioritize speed, precision, and consistency in technical hiring, the interview as a service model has emerged as a specialized solution that addresses a growing skills-based hiring gap. Modern companies recognize that the interview stage, particularly for technical and niche roles, often becomes the bottleneck, not the sourcing stage.

Read our latest blog: Candidate Experience Matters: How to Maintain a Brand while Outsourcing Interviews

Interview as a service platforms solve this by delivering trained domain experts, structured assessments, and technology-enabled tech interview solutions that reduce interviewer bias, increase standardization, and free internal teams to focus on core work. This targeted value is something traditional recruitment firms, by design, are not built to deliver at the same depth.