TL;DR: Replio and Koji are both AI-native tools that replace static survey forms with conversational, AI-moderated interviews that probe for the "why." They sit on the same side of the shift away from flat questionnaires. The difference is depth and modality. Replio is survey-first: you build a survey, and it becomes an AI text conversation that scales to many respondents at once, with auto-generated reports and chart-based analytics. Koji is a full AI research platform: voice and chat interviews, six structured question types in a single study, automatic thematic analysis across every transcript, and transparent self-serve pricing you can start free today. If you mainly want to make existing surveys smarter, Replio is a clean upgrade. If you want a complete research engine — voice interviews, quant + qual in one study, and synthesized reports in hours — Koji goes further.
Quick answer: which one should you pick?
- Choose Replio if your core artifact is a survey and you want to convert it into an AI-led text conversation that asks follow-ups, scales to many respondents, and returns auto-built reports — a fast, lightweight upgrade to form-based research.
- Choose Koji if you want AI-moderated voice or chat interviews, the ability to mix open-ended and structured (scale, choice, ranking, yes/no) questions in one study, automatic thematic analysis across all conversations, and the option to start free and scale on transparent pricing.
Both move past the dead-end of static surveys. The 2026 research climate rewards that move: per Maze's 2026 State of User Research, the share of organizations where research informs all levels of business strategy nearly tripled in a single year — from 8% to 22%. Conversational, AI-moderated research is how lean teams keep up with that demand.
What Replio actually does
Replio's pitch is simple and effective: "transform your surveys into AI conversational interviews." Its strengths are real and squarely survey-oriented:
- Surveys that become conversations — you create a survey, and Replio runs it as an AI-led text interview that asks contextually relevant follow-ups instead of accepting a one-word answer.
- Scales to many at once — multiple interviews run simultaneously, so you collect conversational depth at survey-like volume.
- Auto reports + custom analytics — post-interview reports analyze transcripts, segment responses, and visualize data in charts; you can also ask custom questions of your data and get generated charts back.
- Unlimited teammates — every workspace plan supports unlimited users contributing to interviews, reports, and analytics.
Replio's plans are gated by interview volume rather than transparent per-seat dollars: an entry tier offers around 5 active interviews and 100 completed interviews per month, a higher tier roughly 15 active and 300 completed per month, with a 14-day free trial and no credit card required. That model fits a team that runs a steady cadence of survey-style studies and wants conversational depth without standing up a full research stack. Its trade-offs are modality and breadth: Replio is text-and-survey-centric, so you do not get true voice interviews or a deep, multi-type structured question system in a single study.
What Koji actually does
Koji is built as a complete AI research engine:
- AI-moderated voice and chat interviews that adapt in real time, asking the dynamic follow-up a static survey never would. See AI-moderated interviews and voice vs text interviews.
- Six structured question types — open-ended, scale, single-choice, multiple-choice, ranking, and yes/no — in one study, so you capture quantifiable signal and the qualitative "why." See open-ended and multiple-choice questions.
- Automatic thematic analysis — every transcript is auto-coded and themes are clustered across all conversations. See AI auto-tagging and the thematic analysis guide.
- One-click reports + transcript chat — ask a question across 100 interviews and get a cited answer in seconds via chat with transcripts.
- Bring your own respondents — pull participants from your product and go live the same day, 24/7, with no moderator bias.
From research question to synthesized, auto-coded insight in hours — with no research expertise required.
Head-to-head comparison
| Capability | Replio | Koji |
|---|---|---|
| Core concept | Surveys → AI text conversations | Full AI research platform |
| Voice interviews | No (text-first) | Yes (voice + chat) |
| Structured question types | Survey-style | 6 types in one study |
| Dynamic follow-up questions | Yes | Yes |
| Thematic analysis | Report-level | Automatic across every interview |
| Transcript chat / ask-your-data | Custom analytics | Cited answers across all interviews |
| Pricing model | Volume tiers (5/100 → 15/300) | Free (10 credits); €29/mo; €79/mo |
| Quality gate on responses | Not specified | Only 3+ scored conversations charge credits |
| Time to first study | Self-serve | Minutes, self-serve |
Pricing: the honest breakdown
Replio gates plans by interview volume — roughly 100 completed interviews per month on its entry tier and 300 on the next — with a 14-day free trial. That is predictable for survey-style cadences, but the unit you are buying is "completed interviews," whether or not each one produced usable signal.
Koji is transparent and self-serve: a Free plan with 10 credits to run real interviews today, Insights at €29/month, Interviews at €79/month, and custom Enterprise. Voice interviews cost 3 credits, text costs 1, and — critically — a quality gate means only conversations scoring 3+ consume credits. You never pay for junk responses, so your spend tracks usable insight rather than raw completion count.
Where each one wins
Use Replio when your workflow already revolves around surveys and you want to upgrade them into AI conversations quickly — a smart, low-friction way to add follow-up depth to form-based feedback at scale.
Reach for Koji when you need a true research instrument: continuous discovery voice interviews, churn diagnosis, concept testing, or pricing research — and you want scale questions and open-ended probing living in the same study. The structured-question system is the real differentiator: instead of choosing between a quantitative survey and a qualitative interview, you run one study that does both, then let automatic thematic analysis cluster the open-ended answers for you. Koji also documents its approach to interview data privacy and security and to bias and hallucination mitigation.
Switching from Replio to Koji (or running both)
Teams graduate to Koji for three reasons: voice, breadth of question types, and analysis depth. Voice interviews surface emotion and nuance that text conversations flatten — and Koji runs them 24/7 with no moderator bias. Because every study can blend qualitative and quantitative prompts, you avoid maintaining a separate survey alongside your interviews. And because thematic analysis runs automatically across every transcript — not just inside a single report — patterns across 100 conversations surface without manual coding, a task that traditionally takes researchers four to seven hours of work per hour of interview audio.
Replio still earns its place as a fast survey-to-conversation upgrade for text-based feedback. A practical split: use a lightweight conversational-survey tool for quick form upgrades, and use Koji as the always-on engine for deeper voice discovery, win/loss conversations, and studies that need real structured-question rigor.
One more dimension matters as research gets automated: Koji exposes its studies through an MCP server and API, so you can spin up interviews, pull transcripts, and generate reports directly from tools like Claude — wiring research into the workflows where your team already builds.
The bottom line
Replio and Koji both kill the static survey, replacing it with AI that actually converses. Replio optimizes for turning your existing surveys into AI text interviews quickly and affordably. Koji optimizes for depth and breadth — voice and chat, six structured question types in one study, and automatic thematic analysis — on transparent pricing any team can start free. If smarter surveys are the goal, Replio delivers; if a complete, always-on research engine is the goal, Koji is built for it.
Ready to run real customer interviews? Start with Koji free — 10 credits, no credit card, your first AI-moderated study live in minutes. Get from question to insight 10x faster, with no research expertise required.
