Marketing & GrowthFree tool
Case Study From a Customer Interview
A case study written from your customer interview, with quotes kept as spoken and every claim listed for the customer's reviewer to approve.
Free to start · Opens in your River workspace, ready to edit and share
How to write a customer case study from an interview
A customer case study is a short story, told partly in the customer's own words, about the problem they had, why they chose you and what changed. To write one from an interview, record a conversation that follows that story, then list every claim and the evidence behind it. Draft with exact quotes, giving each result its baseline, period and source, and publish only after the customer approves it in writing.
Plan for the customer's approval from the start, because that is where case studies tend to stall. A reviewer who finds a quote they don't recognize, or a number nobody can trace, will cut it. So keep every claim tied to its evidence, from the first question to the final sign-off.
Settle the terms before the interview
Pick a customer with a clear before and after, a champion who enjoys talking about it, and someone on their side with the authority to approve a story. Ask early whether they can be named. If they can't, an anonymous story about "a 40-person distributor" still works.
When you ask, say what you'll publish, where it will appear and that they will approve every word first. Then agree in writing who reviews the draft and how long they need. For a short quote rather than a full story, a testimonial request email makes the same kind of ask.
Check what the customer gets for taking part, too. In the US, the FTC's Endorsement Guides say a discount, free product or early access can be a material connection1. If readers wouldn't expect the connection, it must be disclosed clearly and conspicuously. A discount in their contract for acting as a reference is one.
Run the interview for stories and numbers
Book 30 to 45 minutes with the person closest to the change, and record it. Ask permission at the start so their yes is on the recording. US federal law needs only one party's consent. But the Reporters Committee for Freedom of the Press lists about 11 states, including California and Florida, that require everyone's2, so ask everyone on the call.
Ask in the order the story will run. Within each topic, use what the user-experience research firm Nielsen Norman Group calls the funnel technique3: broad, open questions first, then narrower ones, then closed questions. Save "how many" and "since when" for the end, so every number arrives attached to a story.
Questions that follow the story
| Part | Ask | Listen for |
|---|---|---|
| Before | "Walk me through how you handled this before." | The old way, and what it cost them |
| Trigger | "What made you look for something new, and why then?" | One specific moment or deadline |
| Choice | "What else did you consider? What nearly stopped you?" | The deciding reason, and the doubt they got past |
| Rollout | "How did the first month go?" | Honest friction, which makes the rest believable |
| Results | "What's different now? How do you measure it?" | A number with its baseline, period and source |
| Advice | "What would you tell a peer considering this?" | A line that works as a pull quote |
Ask how they know
"About eleven days" from memory is a quote. The same figure from their invoicing system is evidence. Ask which one you're hearing, and ask for the report.
List every claim before you write
Before drafting, pull out every claim the story might make: each number, comparison, opinion and line you might quote. Keep them in a claim register, a table with one row per claim. It shows where the story is thin, and it becomes the document the customer's reviewer checks.
Mark the claims
Highlight every figure, before-and-after comparison and quotable sentence. Note who said it and the timestamp.
Label the source
Mark each one as their words, your paraphrase or your calculation. Only their words go inside quotation marks.
Check the numbers
For each figure, note the baseline, the period and where it was measured, then compare it with your own data.
Turn gaps into questions
Where the story needs a number they never gave, write the exact question to send back and leave the space.
Write the case study in their words
Follow the order you asked in: before, trigger, choice, rollout and results, ending on their advice to a peer. Put the change in the headline and a three-line summary at the top. Let quotes carry what only the customer can say, such as how it felt. Background and figures from your own records go in your sentences.
Quote exactly. The New York Times tells its journalists that readers should be able to assume every word between quotation marks is what the speaker said4. They leave out an "um" and may cut a false start. Anything that needs more fixing gets paraphrased, without quotation marks.
US advertising rules agree. The FTC's Endorsement Guides say an ad need not use a customer's exact words unless it presents them as exact, as quotation marks do5. Either way, it can't reword them, or take them out of context, to distort the customer's opinion or experience.
Transcript, 00:14:22, operations lead: "Order to invoice used to sit at, um, about eleven days, and it's four now, most weeks anyway."
Too tidy: "We cut order-to-invoice time by 64%."
Kept honest: "Order to invoice used to sit at about eleven days, and it's four now, most weeks anyway."
In your own sentence: Our account data shows their median order-to-invoice time fell from 10.6 days in the first quarter to 4.1 in the third.
- Filler out, hedges in. "Um" goes. "About" and "most weeks anyway" stay, because they limit the claim.
- No math inside quotes. They never said 64%. It's your arithmetic, so it can't go inside their quotation marks.
- Your data, your voice. The median comes from your records, so it sits in your sentence with its time period.
Check the headline number
Readers will take your headline number as the result they can expect. In the US, FTC staff guidance says endorsements claiming specific results will usually be read that way6, and a line like "Results not typical" won't change it. So either have evidence the result is typical, or state clearly what customers generally achieve.
Check the number against your other accounts first. If this customer is an outlier, put what's typical beside their result, just as plainly: "Most customers cut invoicing time by about a third."
When to involve a lawyer
This guide sums up US rules in plain terms and isn't legal advice. Have a lawyer review any story that makes health, financial or safety claims, compares you with a named competitor, or will run outside the US.
Get sign-off, then keep it current
Send the reviewer the draft and the claim register together, so they can check each claim against its evidence instead of rewriting prose. If they reword a quote, check that the speaker agrees, then use it and note that it came from approval, not the interview. Get the final yes in writing, from the person who agreed to sign off.
A story told in the present tense implies the customer still uses your product. FTC staff guidance says you can use such an endorsement only as long as you have good reason to believe the endorser does still use the product6. Set a review date before their renewal, and update or retire the story if they leave.
Before you publish a case study
- Every quote matches the recording, hedges included
- Each number has a baseline, a period and a source
- The headline result is typical, or what's typical is stated beside it
- Any discount or perk for taking part is disclosed
- The customer approved the final text in writing
- A review date is set before their renewal
Prefer to work from a document? The client case study template has the sections, a results table and a permission email. Or paste your transcript into the box at the top of this page. River builds the claim register, drafts the story with quotes as spoken and lists the questions to send back.
How it works
Start with the interview transcript, exactly as your recording tool exported it, with or without timestamps. Add the account's results data and a line on who signs off if you have them. River lists every claim before it writes, then drafts the case study with quotes kept as spoken. Beside it sits a claim register: each claim with who said it, where it appears in the interview and what it rests on.
Where the interview never gave a number the story needs, River leaves the gap and writes the question to send back. It won't drop a hedge from a quote or borrow a figure from another account. Edit the draft in your workspace, share it, or ask River for a one-page sales version.
Paste the interview
Any export works, with or without timestamps. Add results data and who signs off, if you have them.
River lists every claim
Each quote and number gets a row: who said it, when, and whether it's their words or yours.
Get the draft
The case study in your workspace, with the claim register beside it and questions for anything missing.
Send it for sign-off
Edit anything, ask for a one-page version, and send the register so their reviewer can approve each line.
What you get
- The case study itself, from where they started and what it cost them to what changed
- Quotes reproduced exactly as spoken, with only filler and false starts trimmed and every hedge kept
- A claim register: who said each claim, where in the interview, what backs it and who approves it
- Their stated figures checked against any account data you add, with your own calculations kept outside their quotes
- The headline result checked against any data you add on other customers, with a fairer headline for outliers
- Follow-up questions for missing numbers, plus any discount to disclose and a recheck date before renewal
Common questions
What is a customer case study?
A customer case study is a short, approved account of one customer's experience with your product: the problem they had, why they picked you and what changed. It mixes their own quotes with results backed by numbers and sources. Companies publish them on their websites and send them to buyers who want proof from a peer.
What questions should I ask in a case study interview?
Ask in story order: how they worked before, why they went looking, why they chose you and what nearly stopped them. Then cover the rollout, what's different now and what they'd tell a peer. Open each topic broadly before narrowing to numbers. Note their doubts, too: your next buyer probably shares them, so they make good questions for your website's FAQ section.
How long should a customer case study be?
For a web page, 500 to 1,000 words is usually enough: a headline with the result, a short summary box, then before, decision, rollout and results. Sales teams often also want a one-page version, and a two-line quote for the homepage. Cut anything the customer didn't say or your data can't show, however good it sounds.
Can I clean up a customer's quotes?
Only lightly. Cut filler such as "um" and false starts, but keep the customer's words, their order and every qualifier, such as "I'd say" or "most weeks." When a passage needs more work than that, paraphrase it outside the quotation marks. Changing a quote's meaning, even to make it clearer, turns it into words they never said.
Can I write a case study without an interview?
Yes, but treat every claim as unconfirmed until the customer checks it. If you describe the story in your own words, River drafts from that and marks each claim for the customer's confirmation. For consulting work written up in a final report or deck, the case study generator works from that document instead.
How do I write a case study from a customer interview with River?
Paste the interview transcript into the box at the top of this page, and add results data or approval notes if you have them. River lists every claim, drafts the case study with exact quotes and writes questions for any gaps, all in your free River workspace. Edit it there, share it, or ask for a one-page version.
Is the case study writer free?
Yes, it is free to start. Your case study opens in a River workspace, where you can edit it, share it or ask River to change it. Paid plans add more AI use and access to the most advanced models.
Sources
eCFR. “16 CFR 255.5: Disclosure of material connections.” ecfr.gov (opens in a new tab)
Reporters Committee for Freedom of the Press. “Introduction to the Reporter's Recording Guide.” rcfp.org (opens in a new tab)
Nielsen Norman Group. “The Funnel Technique in Qualitative User Research.” nngroup.com (opens in a new tab)
The New York Times. “Guidelines on Integrity.” nytimes.com (opens in a new tab)
eCFR. “16 CFR 255.1: General considerations.” ecfr.gov (opens in a new tab)
FTC. “FTC's Endorsement Guides: What People Are Asking.” ftc.gov (opens in a new tab)
Built by
Chandler Supple
Co-founder & CEO, River
Chandler has spent the last six years working in AI, building tools for millions of users and Fortune 100 companies. In 2025, he co-founded River to build a new kind of operating system for AI agents.