TL;DR: UserCall and Koji are both AI-moderated voice interview platforms that auto-code qualitative themes — but they optimize for different jobs. UserCall is built to fire short voice micro-interviews at key product moments (onboarding friction, upgrade hesitation, cancellation) and integrates with your product analytics stack. Koji is a broader, research-first platform: voice and chat interviews, six structured question types in one study, automatic thematic analysis, an AI consultant, and self-serve pricing as low as €1 per qualified interview. If your use case is in-product, behavior-triggered voice prompts, UserCall fits well. If you want a full customer-research platform that also runs structured studies, Koji is the broader value.
Quick answer: which one fits?
- Choose UserCall if your priority is triggering short AI voice interviews inside your product after specific events (signup, churn, checkout abandonment) and you live in PostHog, Amplitude, Mixpanel, or Segment.
- Choose Koji if you want a complete research platform — discovery, win/loss, concept tests, pricing studies — with both voice and chat, structured + qualitative questions, and a free tier to start on today.
Both are modern AI-interview tools. UserCall leans into product-led, event-triggered micro-research. Koji is the broader research engine.
What UserCall does
UserCall runs continuous qualitative voice interviews at scale and turns them into structured, evidence-linked themes. Its signature move is trigger-based, in-product interviewing: it fires short AI-moderated voice or text interviews after key moments — signup, onboarding friction, upgrade hesitation, feature adoption, cancellation, or checkout abandonment. Other capabilities:
- AI moderator that asks context-aware follow-up probes to reduce bias.
- Automatic thematic analysis and pattern recognition from transcripts.
- Visual stimulus / prototype testing with screen recording.
- 30+ languages with AI translation and moderation.
- Integrations with PostHog, GA4, Mixpanel, Amplitude, and Segment, plus custom branded interview links and human-in-the-loop review.
UserCall's pricing is transparent and flat-rate, but starts higher than most self-serve research tools:
- Lite — $89/mo ($899/yr): 100 credits, up to 12-minute interviews, 2 links, 30 analysis runs.
- Core — $199/mo ($1,999/yr): 300 credits, up to 25-minute interviews, 5 links, 100 analysis runs.
- Pro — $399/mo ($3,999/yr): 650 credits, up to 45-minute interviews, 10 links, 200 analysis runs, 6 seats.
- Custom for larger needs.
There is no free-forever tier, and the entry plan caps interviews at 12 minutes — fine for micro-interviews, tighter for deep discovery sessions.
What Koji does
Koji is an AI-native customer research platform built for the full range of research, not only in-product micro-prompts:
- AI-moderated voice and chat interviews with real-time follow-up probing in 30+ languages.
- Six structured question types — open_ended, scale, single_choice, multiple_choice, ranking, and yes_no — so one study captures both a measurable score and the conversational reasoning. (See the structured questions guide.)
- Automatic thematic analysis across every transcript, with themes and patterns and supporting quotes.
- One-click reports and an AI consultant you can interrogate about findings.
- A native MCP server to launch studies and pull insights from Claude, Cursor, or ChatGPT.
- Self-serve pricing from free: Start free with 10 credits, no card. Interviews then run as low as €1 per qualified interview and €3 per qualified voice interview. Start with pay as you go. No subscription needed. You pay only for the interviews your study actually uses. Volume pricing and plans are there when you want them. A quality gate means only conversations scoring 3+ ever consume a credit.
Head-to-head comparison
| Dimension | UserCall | Koji |
|---|---|---|
| Core format | AI voice (and text) micro-interviews | AI voice + chat interviews |
| Signature strength | In-product, event-triggered interviewing | Full research platform with structured studies |
| Structured question types | Limited | 6 (open_ended, scale, single/multi choice, ranking, yes/no) |
| Thematic analysis | Yes | Yes — cross-interview theme coding |
| Prototype / stimulus testing | Yes (screen recording) | Yes |
| Product-analytics integrations | PostHog, GA4, Mixpanel, Amplitude, Segment | Via MCP + exports |
| Free tier | No | Yes — 10 credits |
| Entry price | $89/mo (12-min cap) | Free, then from €1 per qualified interview |
| Languages | 30+ | 30+ |
| Developer / agent access | — | Native MCP server |
Where they genuinely differ
Trigger model vs research platform. UserCall's edge is firing voice interviews automatically off product events through native analytics integrations — ideal for always-on, in-product feedback at specific moments. Koji is designed as a research workstation: you scope a study, choose the audience, mix structured and open questions, and get a synthesized report. Both auto-code themes; the difference is how the conversation gets started and how broad the research workflow is.
Price of entry. UserCall starts at $89/month with no free-forever plan and a 12-minute interview cap on the entry tier. Koji starts free and moves to pay as you go with no subscription, at as low as €1 per qualified interview, letting you validate the product on real data before committing, and run interviews without a length cap that forces an upgrade.
Breadth of question types. Koji's six structured question types let a single study double as a survey and an interview, capturing an NPS or CSAT number alongside the conversational "why." That makes Koji a stronger fit when you need quantitative measures and qualitative depth in one place.
What the 2026 data says
The shift to AI-moderated, conversational research is accelerating:
- AI embedded in research software rose from 62% to 66% of researchers in 2026, while general-purpose chatbot use fell from 75% to 67% — teams want purpose-built research AI (State of User Research 2026).
- Customer interviews are the #1 method at 86% adoption, ahead of usability testing (84%) and surveys (77%).
- 63% of teams cite time and bandwidth as their biggest constraint — exactly what AI-moderated interviewing removes by running and analyzing conversations automatically.
- Research being essential to all levels of strategy tripled from 8% to 22% year over year (Qualtrics 2026), and teams not using AI are 4x more likely to lose organizational influence.
Bottom line
UserCall is a sharp tool for what it does best: triggered, in-product AI voice micro-interviews wired into your analytics stack. If that is your exact need and the $89+ entry point fits, it is a strong pick. But if you want a complete research platform — voice and chat, six structured question types, cross-interview theme coding, an AI consultant, an MCP server, and a free tier to start on — Koji delivers broader research value at a lower entry price. For most product, founder, and research teams that need more than event-triggered micro-prompts, Koji is the more flexible and economical choice.
Common research jobs, mapped
- Always-on, in-product feedback — UserCall is purpose-built here: triggered voice prompts at signup, onboarding friction, upgrade hesitation, and cancellation, fired straight from your analytics events. This is its clearest advantage.
- Dedicated discovery and win/loss studies — Koji shines when you scope a study, recruit or share a link, and need both structured and open-ended answers. Its thematic analysis codes themes across every transcript automatically.
- Concept and pricing tests — Both support stimulus testing; Koji captures ranking and choice responses natively alongside the spoken reaction, so you get the number and the reasoning together.
- Programmatic and agent-driven research — Koji's native MCP server lets you launch studies and pull insights from Claude, Cursor, or ChatGPT — useful for teams automating continuous discovery.
- Budget-sensitive teams — Koji starts free, then you pay only for the interviews your study actually uses: as low as €1 per qualified interview with no subscription needed, and no interview-length cap, versus UserCall's $89/month entry plan and 12-minute limit on the lowest tier.
The honest summary: UserCall is the better instrument for event-triggered micro-interviews inside your product; Koji is the broader, lower-cost research platform for everything from discovery to reporting.
Try Koji free
Run AI-moderated voice and chat interviews, capture structured and open-ended answers in one study, and get an auto-coded report with quotes in hours — no recruiting agency, no moderator, no research expertise required. Start free with 10 credits and see how far question-to-insight in hours can take your roadmap.
