The hiring manager had found a perfect candidate—a senior engineer in New Zealand with exactly the experience they needed. One problem: there was no reasonable overlapping time for interviews between Auckland and San Francisco. Every option meant someone awake at 3am.
They passed on the candidate. Six months later, they still hadn't filled the role.
Synchronous interviews create a geographic filter that has nothing to do with engineering ability. If your process requires 6+ hours of interviews in overlapping time zones, you've excluded large swaths of the global talent pool before evaluating a single skill.
Async interviews solve this. They're not right for every situation, but implemented well, they can dramatically expand your reach while maintaining signal quality[^1].
When Async Makes Sense
Async interviews aren't universally better—they're better in specific contexts.
| Scenario | Async Advantage |
|---|---|
| 6+ hour time zone difference | Scheduling is impossible otherwise |
| High-volume screening | Scale without recruiter time |
| Candidate schedule constraints | They interview when convenient |
| Reducing interview bias | Standardized, reviewable |
| Global hiring | Level playing field across geographies |
| Scenario | Sync Still Better |
|---|---|
| Final-round decisions | Chemistry matters |
| Complex back-and-forth | Real-time clarification needed |
| Assessing collaboration | Need to see how they interact |
| Executive roles | Relationship building is critical |
The hybrid approach works well: async for early stages, sync for final rounds. This gives you the efficiency benefits of async while preserving relationship-building where it matters most.
Async Interview Formats
Video Response Questions
Candidates record video responses to predetermined questions.
How it works:
- You provide 3-5 questions in text
- Candidate records video responses (usually 1-5 minutes each)
- Interviewers review asynchronously
- Feedback aggregated, decision made
Good for: Communication assessment, behavioral questions, culture fit screening.
| Advantage | Consideration |
|---|---|
| See communication style | Some candidates hate video |
| Can review multiple times | Production quality varies |
| Multiple reviewers, no scheduling | Less spontaneous than live |
| Standardized questions | Can feel impersonal |
Platform options: HireVue, Spark Hire, VidCruiter, custom (Loom submissions)
Written Technical Assessment
Candidates answer technical questions in writing, asynchronously.
How it works:
- Provide technical questions (design, problem-solving, experience-based)
- Candidate responds in written form
- Reviewers evaluate quality of thinking
Good for: Technical communication, depth of thought, architectural thinking.
Example questions:
- "Describe how you would design a system that [specific requirement]"
- "Walk through how you debugged a complex production issue"
- "What trade-offs would you consider when choosing between [X and Y]?"
| Advantage | Consideration |
|---|---|
| Written communication matters | Not everyone writes well |
| Can see thinking structure | Time investment for candidates |
| Review on your schedule | Can't probe for more detail |
Take-Home Coding Project
Candidates complete a coding exercise on their own time.
How it works:
- Provide problem and requirements
- Candidate completes in their environment
- Reviewers assess code quality, approach, completeness
Best practices:
- Time-bound (recommended 2-4 hours of work)
- Clear scope and evaluation criteria
- Reflective of actual work
- Paid for longer exercises
| Advantage | Consideration |
|---|---|
| Real coding environment | Time burden on candidates |
| No interview anxiety | Potential for outside help |
| Review actual code | Calibration across submissions |
Code Review Exercise
Candidates review existing code asynchronously.
How it works:
- Provide a PR or codebase section
- Candidate writes a review as they would for a colleague
- Evaluate what they catch, how they communicate
Good for: Senior engineers, assessing judgment and communication.
| Advantage | Consideration |
|---|---|
| Realistic task | Requires good sample code |
| Shows communication style | Different standards |
| Low time burden | May miss some collaboration signals |
System Design Document
Candidates write a design document for a given problem.
How it works:
- Provide a problem statement with constraints
- Candidate writes design document
- Evaluate architecture thinking, trade-off analysis
Good for: Senior/staff engineers, architectural assessment.
| Advantage | Consideration |
|---|---|
| Deep thinking visible | Significant time investment |
| Written artifact for review | Writing skill variance |
| Can assess organization and structure | Hard to ask clarifying questions |
Implementation Best Practices
Clear Instructions
Async interviews fail when candidates don't understand expectations.
| What to Communicate | Why It Matters |
|---|---|
| Time expectation | "This should take ~2 hours" |
| Format requirements | Video length, document format |
| Evaluation criteria | What you're looking for |
| Deadline | When to submit by |
| Technical setup | Platform requirements |
| Questions process | How to ask clarifying questions |
Standardization
Every candidate should receive identical prompts for fair comparison.
| Standardize | Why |
|---|---|
| Questions | Same assessment across candidates |
| Time limits | Comparable effort |
| Evaluation rubric | Consistent scoring |
| Reviewer training | Aligned expectations |
Reasonable Time Expectations
| Exercise Type | Reasonable Time | Pushing It |
|---|---|---|
| Video response (3-5 Qs) | 30-45 min | 60+ min |
| Written technical | 1-2 hours | 3+ hours |
| Take-home coding | 2-4 hours | 6+ hours |
| Code review | 30-60 min | 90+ min |
| Design document | 2-4 hours | 6+ hours |
Respect candidate time. Excessive async requirements feel like unpaid work.
Candidate Experience
| Practice | Impact |
|---|---|
| Acknowledge submission promptly | Shows respect |
| Provide timeline for response | Reduces anxiety |
| Allow questions before submission | Clarifies expectations |
| Provide feedback (when possible) | Builds goodwill |
Evaluation and Calibration
Scoring Rubrics
Every async exercise needs a scoring rubric.
Example: Video Response Rubric
| Dimension | 4 (Strong) | 3 (Acceptable) | 2 (Concerning) |
|---|---|---|---|
| Clarity | Clear, well-organized response | Generally clear, some wandering | Hard to follow |
| Depth | Specific examples, thoughtful | Some detail, mostly surface | Vague, generic |
| Communication | Articulate, engaging | Adequate, professional | Unclear, uncomfortable |
| Relevance | Directly addresses question | Mostly addresses question | Misses the point |
Multiple Reviewers
Have at least two people review each async submission independently before discussing. This prevents anchoring and reveals evaluation disagreements.
Calibration Sessions
Run calibration regularly:
- All reviewers evaluate the same submission
- Compare scores
- Discuss disagreements
- Align on standards
Hybrid Approach: Async + Sync
The most effective process combines async efficiency with sync depth.
Recommended Flow
| Stage | Format | Purpose |
|---|---|---|
| Application review | Async | Resume, basic qualification |
| Video intro (optional) | Async | Communication screen |
| Technical screen | Async or sync | Basic technical validation |
| Take-home or written | Async | Deep technical assessment |
| Live coding/discussion | Sync | Collaboration, clarification |
| Behavioral interview | Sync | Culture, relationship |
| Final conversation | Sync | Closing, questions |
For international candidates with significant time zone difference:
- Stages 1-4: Fully async
- Stages 5-7: Sync (find one or two windows that work)
This limits synchronous time to 2-3 hours, which is manageable even with difficult time zones.
Platform Considerations
| Platform Type | Examples | Best For |
|---|---|---|
| Video interview platforms | HireVue, Spark Hire | Structured video response |
| Coding platforms | CoderPad, HackerRank | Timed coding exercises |
| General video | Loom, custom | Flexible video submission |
| Document-based | Notion, Google Docs | Written exercises |
| All-in-one ATS | Greenhouse, Lever | Integrated workflow |
Choose platforms that integrate with your ATS and provide good candidate experience.
Common Pitfalls
| Pitfall | Problem | Solution |
|---|---|---|
| Too much async | Candidates feel like they're applying to a black box | Add human touchpoints |
| No sync at all | Miss collaboration signals | Include at least one live conversation |
| Unclear expectations | Varied quality submissions | Detailed instructions |
| No feedback | Candidates feel ghosted | Communicate timeline, provide closure |
| Excessive length | Candidate drop-off | Respect time, keep exercises reasonable |
The company that passed on the New Zealand candidate? They implemented async interviews six months later. Their next international hire completed a take-home project and video responses asynchronously, then did two final sync interviews scheduled at the one overlapping hour that worked. They hired a brilliant engineer they would have missed entirely with their old process.
The talent pool is global. Your interview process should be too.
References
[^1]: SmithSpektrum async interview implementation data, 2021-2026. [^2]: Remote.com, "Global Hiring Guide," 2025. [^3]: LinkedIn Talent Solutions, "Future of Recruiting," 2025. [^4]: SHRM, "Video Interview Best Practices," 2024.
Implementing async interviews? Contact SmithSpektrum for process design and platform recommendations.
Author: Irvan Smith, Founder & Managing Director at SmithSpektrum