YOU THINK THATYou can cancel your gym membership anytime
"Member may cancel by providing written notice. A processing period of 30 business days applies."
Sounds simple enough — just send a letter and you're out. A month's notice? That's pretty normal.
See what this really means. Flip it!
BUT IN REALITYThey keep charging while you wait
$133 to leave a $29/month gym
"30 business days" is 6 weeks. Two more payments plus a $75 "processing fee."
← Flip back
Real documents. Real fine print. Pick one and see what’s hiding.
Staying Connected
You agreed to more than you think
Peace of Mind
What’s not covered?
Future Fund
The rate isn’t the whole story
My New Place
Your landlord’s favorite clause
Morning Workout
Good luck canceling
Furry Friend
More than a promise
Weekend Savings
The savings aren’t free
Celebration!
Who pays when it rains?
The Hackathon
What did we all agree to?
First Day of Work
Read this before you start
Trip of a Lifetime
Can they really keep the prize?
Check-up Time
What you’re really signing
Dream Home
Your house, their rules
Dream Getaway
Check-out is forever
Your document is analyzed by Claude and never stored. No data leaves the Anthropic API.
AI analysis — not legal advice. Always consult an attorney for important decisions.
Frequently Asked Questions
Everything you need to know before uploading a document.
What is FlipSide?
FlipSide shows you what the other side intended when they wrote your document. Upload any contract, agreement, or policy you didn't draft — a lease, insurance policy, gym membership, Terms of Service — and FlipSide reads it from the drafter's perspective, not yours.
Each clause gets a flip card. The front shows what a trusting reader sees: the reassuring headline, the comforting language. Flip it, and the back reveals what an expert catches: the trick, the risk score, the figure that matters, and what you should actually read.
It's based on a methodology called "Think Like a Document" — instead of reading from your perspective, read from the perspective of the party who wrote it. FlipSide applies that principle at scale using AI.
FlipSide treats a $2 coupon with the same seriousness as a $500,000 corporate lease. Because the tricks are the same — only the stakes change.
How does it work?
FlipSide runs two AI models in parallel the moment you upload:
Flip Cards (Claude Haiku 4.5): Pre-scans your document, then launches parallel workers that generate full flip cards — front and back — in ~8 seconds.
Expert Verdict (Claude Opus 4.6): Builds a one-screen verdict from t=0 — verdict tier, main risk, power ratio, jurisdiction detection, risks, and a self-reviewed checklist.
Cards appear in seconds. Six expert analyses build in parallel: a verdict, document archaeology, worst-case scenario, walk-away number, hidden combinations, and negotiation playbook. You can start flipping cards while Opus 4.6 is still thinking. Expert reports appear as each one finishes.
After the analysis, you can ask follow-up questions ("What happens if I'm 3 months late on rent?"), message the company with a professional letter citing specific clauses, or request a counter-draft that rewrites unfair clauses with negotiable alternatives.
Your data & privacy
FlipSide stores nothing. Your document is not saved anywhere — not to disk, not to a database, not to a temporary file. It exists only in your browser session's memory and is gone when you close the tab or analyze a new document.
No disk writes. The server has no file system storage, no database, no logging of document content.
No external services. Your document is never sent to any third party. The only external call is to the Anthropic API (Claude) for analysis.
No analytics or tracking. No cookies, no user accounts, no telemetry. FlipSide doesn't know who you are.
Memory only. Documents exist in server memory during your active session and are released when the session ends. Nothing survives a server restart.
The 14 sample documents on this page are embedded directly in the application code — they are not fetched from any external source.
What does Claude keep?
When you upload a document, it is sent to the Anthropic API for analysis by Claude Haiku 4.5 (fast card scan) and Claude Opus 4.6 (expert verdict). Here is what Anthropic does and does not do with your data:
Not used for training. Anthropic does not use API inputs to train its models. Your document will not become part of Claude's training data.
Safety monitoring. Anthropic may retain API inputs for up to 30 days for trust and safety purposes (detecting abuse, complying with legal obligations). After that, it is deleted.
No sharing. Anthropic does not share your API data with third parties except as required by law.
Prompt caching. FlipSide uses Anthropic's prompt caching feature, which caches the system instructions (not your document) for performance. This reduces cost and latency but does not affect your document's privacy.
In short: Anthropic processes your document to generate the analysis, may retain it briefly for safety, and then deletes it. FlipSide itself keeps nothing at all.
FlipSide was built during the Built with Claude Hackathon (February 2026) to prove a point: legal document analysis shouldn't be locked behind $2,500/hour BigLaw fees. Everyone signs contracts. Not everyone can afford to understand them.
The entire codebase is open source under the MIT License — free for anyone to use, modify, and distribute. There are no paid tiers, no premium features, no subscriptions, and no plans to add any.
The only operational cost is the Anthropic API, which processes each document. During the hackathon, there are no cost constraints. The vision: making document literacy accessible to everyone, not just people who can afford a lawyer.
Is this legal advice?
No. FlipSide is an analysis tool, not a law firm. It helps you understand what a document says and what the drafter may have intended — but it is not a substitute for professional legal advice.
FlipSide does not provide legal opinions or recommendations.
FlipSide is not your attorney and no attorney-client relationship is created.
For important decisions — signing a lease, accepting employment terms, buying insurance — always consult a qualified attorney.
Think of FlipSide as a flashlight: it shows you what's there. What you do with that knowledge is up to you and your lawyer.
Who built this?
Henk van Ess finds the story in public data. An internationally recognized expert in AI-powered digital research and open-source intelligence (OSINT), his methods are sought after by Pulitzer winners, NGOs, research firms, and law enforcement. Assessor for the International Fact-Checking Network (IFCN) and its European counterpart EFCSN. Early Bellingcat contributor. Author of multiple books on internet research. 10,000+ newsletter subscribers from BBC, NYT, Reuters, Europol, Harvard, MIT.
He does not write code. Every line of FlipSide — 3,861 lines of Python backend and 10,748 lines of frontend — was built through conversation with Claude Opus 4.6 in 5 days. The prompts were the product. The AI was the builder.
SCORE 0/100 · NO TRICKS DETECTED · WRITTEN BY OPUS 4.6
We asked Claude Opus 4.6 with extended thinking: "Write the fairest possible service agreement clause. Every provision must be symmetrical — what applies to the customer must equally apply to the company. Show your reasoning for each section." This is what it wrote.
1. What we promise each other.
We will provide the service as described at the time you signed up. If we need to change what's included, we will notify you 30 days in advance, and you may cancel without penalty if you disagree. You agree to use the service in good faith and pay the agreed amount on time. If your payment fails, we will notify you and give you 14 days to resolve it. No late fees. No penalties. No collection agencies.
Opus reasoning: Most service agreements give the provider unlimited discretion to change terms while locking the customer into the original price. Symmetry means both parties get the same notice period and the same exit rights when terms change.
2. Either of us can leave.
You may cancel at any time. We may cancel with 30 days' written notice. If you have paid in advance, you will receive a prorated refund for the unused period. No cancellation fees. No early termination penalties. No "retention department" calls.
Opus reasoning: The most common trick in consumer contracts is asymmetric exit — the company can terminate immediately "for any reason" while the customer faces penalties, lockout periods, or forfeiture of prepaid amounts. Fair means equal exits.
3. If something goes wrong.
If the service fails, we will work to restore it within 48 hours and credit you for the downtime. If we cause you measurable financial harm through negligence, our liability is capped at 12 months of fees you have paid — and the same cap applies to your liability to us. Neither party is liable for circumstances beyond their control.
Opus reasoning: Typical agreements cap the company's liability at "fees paid in the last month" while leaving the customer's liability unlimited. A fair cap is symmetrical and substantial enough to be meaningful — 12 months, not 1.
4. Disagreements.
We will first attempt to resolve any dispute through direct conversation. If that fails, we will use mediation with a mutually agreed mediator, splitting the cost equally. If mediation fails, either party may pursue resolution in the courts of their own jurisdiction. No forced arbitration. No class action waivers. No "prevailing party pays attorneys' fees" clauses that discourage small claims.
Opus reasoning: Forced arbitration with a company-selected arbitrator in a company-chosen jurisdiction is the single most powerful trick in consumer contracts. It eliminates your practical ability to dispute anything. Fair means you choose your own forum.
5. Your content stays yours.
Anything you create, upload, or store using the service belongs to you. We may use it only to provide you the service. We will not sell it, license it, or use it for training, advertising, or any purpose beyond delivering what you asked for. When you leave, you may export your data at any time, and we will delete our copies within 30 days.
Opus reasoning: "Content Grab" is the second most common trick — buried in ToS, you grant a "worldwide, irrevocable, perpetual license" to everything you upload. Fair means your data is yours, period. The company is a custodian, not an owner.
6. Changes to this agreement.
We may update these terms. For minor clarifications, we will post the update and notify you. For material changes — anything affecting price, service scope, your rights, or dispute resolution — we will notify you 30 days in advance and require your explicit consent. If you do not consent, you may leave with a full refund of any prepaid amounts. We will never interpret continued use as acceptance of material changes.
Opus reasoning: "Continued use constitutes acceptance" is how companies unilaterally rewrite the deal after you've signed. Fair means material changes require your actual agreement — not your silence.
7. Plain language guarantee.
This agreement is written in plain language because we believe you should understand what you're agreeing to. If any provision is ambiguous, it will be interpreted in favor of the party who did not draft it — which, in this case, is you.
Opus reasoning: The legal doctrine of contra proferentem (interpret against the drafter) exists precisely because the drafter chose the words. Making this explicit signals good faith and removes the incentive to write deliberately vague provisions.