CORE-01
One primary action, clearly the strongest
When two actions look equally important, people hesitate or pick the wrong one.
Applies to: Any screen with a main task.
Irreplaceable › Guides › UX review checklist
Checklist · Design crit and UX audit
The UX review checklist: 102 rules
Every rule the design crit and Crit Gate check a screen against, written out. Use it for a design crit, a UX audit or your own last look before handoff. Each rule says where it applies, why it matters and how severe a miss is.
By Sarit Elisha, founder of Irreplaceable · Updated October 10, 2026
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How severe is a miss?
Every rule carries a severity, so a review starts with what matters most.
- BlockerPeople can't finish, or the screen harms them: money, data, consent.
- MajorMany people will hesitate, misread or make a mistake.
- MinorFriction or polish. Worth fixing, rarely urgent.
24 rules
Core UX
Basics every screen needs, AI or not.
CORE-02
The thing people came to see is the first thing they see
A key number or status buried under decoration gets missed.
Applies to: Screens that show a result, total or status.
CORE-03
Labels say what happens, not 'OK' or 'Continue'
A specific verb ('Pay $412', 'Delete 3 files') tells people the consequence before they commit.
Applies to: Buttons and links.
CORE-04
Money shows currency, what it includes and what changed
An unexplained total, or one that differs from what was asked for, breaks trust at the worst moment.
Applies to: Totals, prices and amounts.
CORE-05
Irreversible actions are named as such and confirmed or undoable
People need a last look, or a way back, when a mistake is expensive.
Applies to: Delete, send, pay, publish and other hard-to-reverse actions.
CORE-06
Empty states explain what goes here and how to start
A blank area reads as broken and leaves people without a next step.
Applies to: Lists, searches, dashboards and first-run screens.
CORE-07
Errors say what went wrong and how to fix it, next to the problem
'Something went wrong' leaves people stuck; an error far from its field is missed.
Applies to: Forms and anything that can fail.
CORE-08
Waiting shows progress and what is happening
A spinner with no context feels longer and makes people retry or leave.
Applies to: Anything that takes more than a moment.
CORE-09
Small or low-contrast text that carries meaning
Fine print that holds a key fact (a fee, a non-refundable term) is easy to miss and reads as hiding it.
Applies to: Text and controls.
CORE-10
Every field has a visible label, not only a placeholder
Placeholders disappear on typing, so people lose track of what each field wants.
Applies to: Inputs.
CORE-11
Every action gets visible feedback
Without a response, people don't know if the tap worked, tap again, and create duplicates or give up.
Applies to: Every action people can take on the screen.
CORE-12
Words match the user's world, not the system's
Internal names, codes and database terms make people translate before they can act.
Applies to: Labels, headings and messages.
CORE-13
A way back, out or undo is always visible
People explore when they know they can return. Without Back, Cancel or Undo they hesitate or get stuck.
Applies to: Screens inside a flow, modals and edits.
CORE-14
The same thing looks and works the same everywhere
Two styles for one action, or one style for two actions, make people relearn the screen as they go.
Applies to: Repeated components and patterns on the screen.
CORE-15
Errors are prevented, not just reported
Constraints, good defaults and pickers stop wrong input before it happens, which beats any error message.
Applies to: Inputs, pickers and destructive controls.
CORE-16
Help is where the question comes up
A hint next to a hard field gets read; a help centre link at the bottom doesn't.
Applies to: Complex fields, settings and first use.
CORE-17
Frequent users have a faster path
Shortcuts, bulk actions and remembered choices keep experts fast without getting in a newcomer's way.
Applies to: Screens people use often or in bulk.
CORE-18
Every element earns its place
Each extra element competes with the ones that matter and slows the main task.
Applies to: Dense screens.
CORE-19
People can tell where they are
Without a title, active navigation state or breadcrumb, people lose their place and can't predict where Back goes.
Applies to: Screens inside an app or site.
CORE-20
The main action is within thumb reach
Actions at the top of a tall phone screen need two hands or a stretch, and get missed or delayed.
Applies to: Primary actions on phone screens.
CORE-21
The keyboard fits the field and doesn't hide it
Email, number and phone fields need their own keyboard, and the field and its error must stay visible above the keyboard.
Applies to: Text fields on phone screens.
CORE-22
Required and optional are clear, and input formats are forgiving
Guessing which fields are required, or being rejected for a space in a card number, causes most form errors.
Applies to: Forms.
CORE-23
Data is easy to scan and compare
Numbers aligned on the right with consistent units, clear headers and sensible sorting let people compare at a glance.
Applies to: Tables, lists and numbers.
CORE-24
Grouping and hierarchy show the structure
Related things close together and a clear order of headings let people see the structure before they read it.
Applies to: Any screen with more than a few elements.
18 rules · the full guide
AI UX
How AI features act, admit uncertainty, ask for consent and recover. From the Irreplaceable AI UX checklist.
AIUX-01
Show the plan before any costly or shared action
People can't undo what they never saw. A plan turns a surprise into a decision.
Applies to: Agents that book, send, pay or change things.
See it done right and wrongAIUX-02
Ask one clear question when the request is ambiguous
Guessing on ambiguity causes costly mistakes. Asking five questions every time causes friction.
Applies to: Agents that book, send, pay or change things.
See it done right and wrongAIUX-03
Let people edit the plan before it runs
Steering before acting beats undoing after.
Applies to: Agents that book, send, pay or change things.
See it done right and wrongAIUX-04
Give an undo window for anything sent or deleted
Sending and deleting can't be taken back. A few seconds of undo covers most mistakes.
Applies to: Anything AI writes, edits or runs for a while.
See it done right and wrongAIUX-05
Keep the original when AI rewrites or edits
People need to see what changed and get their own words back.
Applies to: Anything AI writes, edits or runs for a while.
See it done right and wrongAIUX-06
Let people stop long generations
Control matters most while it's still running.
Applies to: Anything AI writes, edits or runs for a while.
See it done right and wrongAIUX-07
Say “I'm not sure” and show sources when unsure
Honest uncertainty builds trust that lasts. Confident mistakes break it.
Applies to: Answers, summaries and recommendations.
See it done right and wrongAIUX-08
Don't invent precision
Numbers like “92% match” sound scientific but give people nothing to act on.
Applies to: Answers, summaries and recommendations.
See it done right and wrongAIUX-09
Show where every claim came from
A claim people can check is a claim people can trust.
Applies to: Answers, summaries and recommendations.
See it done right and wrongAIUX-10
Ask before remembering anything sensitive
Health, money and family details need consent, not silent memory.
Applies to: Memory, permissions and personal data.
See it done right and wrongAIUX-11
Limit permissions to the task, with an end date
Forever access to everything is a risk that never goes away.
Applies to: Memory, permissions and personal data.
See it done right and wrongAIUX-12
Leave consent boxes unchecked
A pre-checked box isn't consent, and in the EU it isn't legal.
Applies to: Memory, permissions and personal data.
See it done right and wrongAIUX-13
Say it's an AI, upfront
People have a right to know when they're talking to a machine.
Applies to: Assistants, chatbots, generated content.
See it done right and wrongAIUX-14
Label AI-generated images and text
People decide differently when they know something is generated.
Applies to: Assistants, chatbots, generated content.
See it done right and wrongAIUX-15
Don't fake feelings to keep people engaged
Emotional pressure from a machine is manipulation, especially for kids.
Applies to: Assistants, chatbots, generated content.
See it done right and wrongAIUX-16
Say what happened and what to do next
An error message is a moment to help, not to blame.
Applies to: Errors, refusals and high-stakes moments.
See it done right and wrongAIUX-17
Show a way to a person when stakes are high
Money, health and legal moments need a human exit.
Applies to: Errors, refusals and high-stakes moments.
See it done right and wrongAIUX-18
Explain a refusal and offer what you can do
A bare “I can't help” is a dead end.
Applies to: Errors, refusals and high-stakes moments.
See it done right and wrong50 rules · the full guide
Behavioral
Behavioral science and cognitive psychology: how people notice, decide, remember and act, and the dark patterns that exploit it.
BEH-01
Few enough choices to decide (Hick's law, choice overload)
Every extra option slows the decision, and too many make people give up or pick at random. Group, recommend one, or hide advanced options.
Applies to: Screens that ask people to choose: plans, options, settings, menus.
BEH-02
Defaults serve the user, not the business
Most people keep the default. A pre-ticked add-on, newsletter or data-sharing box is a choice made for them, and erodes trust when they notice.
Applies to: Pre-selected options, toggles and checkboxes.
BEH-03
Anchors and decoys are honest
A crossed-out price that was never charged, or a decoy plan that exists only to push another, is anchoring used against people; regulators treat fake reference prices as deceptive.
Applies to: Prices, plans and comparisons.
BEH-04
Cognitive load fits one step
Working memory holds only a few things at once. Asking for everything on one screen raises errors and drop-off; split it, prefill it, or ask later.
Applies to: Forms, onboarding and dense screens.
BEH-05
Recognition over recall
Making people remember a code, a choice or a rule from an earlier step causes mistakes. Show it where it's needed.
Applies to: Anything people must remember from a previous screen.
BEH-06
Progressive disclosure: the essential first
Showing every detail up front buries the next step. Lead with what most people need and reveal the rest on demand.
Applies to: Settings, advanced features and long content.
BEH-07
Progress is visible (goal gradient)
People speed up as they see the end and abandon when they can't tell how far it is. Show steps or progress, and start it a little ahead if a step is already done.
Applies to: Multi-step flows, onboarding and profiles.
BEH-08
The end of the experience lands well (peak-end rule)
People judge an experience by its peak and its end. A flat or confusing ending colours the whole flow; confirm what happened and what comes next.
Applies to: Confirmation, success and end-of-flow screens.
BEH-09
The ask comes at a moment of motivation and ability
A prompt works when people want to and can act now (Fogg model). Asking at the wrong moment trains them to dismiss it.
Applies to: Prompts to act: upgrades, invitations, reminders.
BEH-10
Framing doesn't mislead (framing effect, loss aversion)
'90% success' and '10% failure' feel different though they're the same. Loss-framed scare copy pushes decisions people later regret.
Applies to: Risks, fees, results and AI output.
BEH-11
Social proof is real and relevant
'12 people are looking at this' that isn't true, or reviews from another product, is fake social proof and a recognised dark pattern.
Applies to: Reviews, counts of other users, badges.
BEH-12
No false urgency or scarcity
Countdown timers that reset and fake 'only 2 left' pressure people into choices; regulators in the EU, UK and US act against them.
Applies to: Timers, stock counts and limited offers.
BEH-13
Leaving is as easy as joining (no roach motel, no confirmshaming)
Hiding cancel, or wording the decline button to shame ('No, I don't like saving money'), keeps people by friction and guilt, and costs trust and often legal exposure.
Applies to: Cancel, unsubscribe, decline and opt-out paths.
BEH-14
No hidden costs, sneaking or forced continuity
Fees revealed at the last step, items added to the basket, or a free trial that silently becomes paid exploit commitment and inattention.
Applies to: Checkouts, sign-ups and consent.
BEH-15
Habit loops respect the user's own goal
Streaks and variable rewards build habits; aimed at engagement for its own sake they turn into compulsion and churn once people notice.
Applies to: Notifications, streaks and engagement loops.
BEH-16
Automation invites checking, not blind trust (automation bias)
People over-trust confident systems and stop checking. Show sources and uncertainty where a wrong answer costs something.
Applies to: AI suggestions, recommendations and automation.
BEH-17
Frequent actions are big and close (Fitts's law)
The time to hit a target grows with distance and shrinks with size. A main action tucked in a corner, or tiny and far from where the thumb or cursor is, slows every use.
Applies to: Primary and frequent actions.
BEH-18
The one important thing stands out (isolation effect)
People remember and notice what differs from its surroundings. When five things are highlighted, nothing is.
Applies to: Screens with one thing that matters most.
BEH-19
Key items sit first or last (serial position effect)
People remember and choose the first and last items best; the middle gets skipped. Bury the important option in the middle and it's missed.
Applies to: Lists, menus and navigation.
BEH-20
Long information is chunked
People hold about four chunks at once. '4829 1173 0062' is read and checked; '482911730062' is mistyped.
Applies to: Long numbers, codes, IBANs, phone numbers and long lists.
BEH-21
Familiar conventions, unless breaking them clearly helps (Jakob's law)
People spend most of their time in other products and expect yours to work the same. A novel pattern costs learning on every first use.
Applies to: Icons, navigation, controls and their placement.
BEH-22
The product absorbs the complexity, not the user (Tesler's law)
Some complexity can't be removed, only moved. Making people format a date, pick a timezone or know a code shifts the work and the errors to them.
Applies to: Inputs, formatting and setup.
BEH-23
It feels fast: instant feedback, then progress (Doherty threshold)
Responses under ~400 ms keep people in flow; slower ones need immediate acknowledgement, skeletons or optimistic updates, or people tap again and leave.
Applies to: Actions that take time: search, save, AI answers.
BEH-24
Unfinished work is visible and easy to resume (Zeigarnik effect)
People remember unfinished tasks and want to close them. Showing what's left and where to pick up turns that pull into completion, instead of starting over.
Applies to: Long tasks, drafts and multi-step setup.
BEH-25
A small first step before a big ask (commitment and consistency)
People who take a small step tend to continue. Asking for everything at once, before any commitment, loses most of them.
Applies to: Onboarding and big asks.
BEH-26
Value comes before the ask (reciprocity)
People give back after they receive. A sign-up or data request before they've seen any value feels like a toll and gets abandoned or faked.
Applies to: Sign-up walls, permission and data requests.
BEH-27
Authority signals are real and relevant
People defer to authority cues. A badge, title or endorsement that isn't real or doesn't apply borrows trust it hasn't earned.
Applies to: Expert badges, certifications, 'recommended by'.
BEH-28
Switching is made easy (status quo bias)
People stick with what they have even when the new option is better. Imports, defaults carried over and a clear 'what changes' lower the cost of moving.
Applies to: Migrations, new versions and switching from a competitor.
BEH-29
Things look as interactive as they are (affordances and signifiers)
Flat text that's secretly a button gets missed; a card that looks clickable but isn't gets tapped in frustration.
Applies to: Buttons, links, cards and anything clickable or static.
BEH-30
Same look, same behaviour (Gestalt similarity)
People assume things that look alike work alike. A blue word that's a link in one place and a label in another breaks that, and they stop trusting the visual language.
Applies to: Repeated elements: links, buttons, tags, statuses.
BEH-31
Built for scanning: the key words come first
People scan in F and Z patterns and read the first words of lines and headings. Front-load what matters; a heading that starts with 'In order to' hides it.
Applies to: Headings, list items and text people scan.
BEH-32
Important information doesn't look like an ad (banner blindness)
People ignore anything shaped and coloured like a banner. A real warning in an ad-like box is skipped.
Applies to: Important notices, warnings and offers.
BEH-33
Changes are shown where people are looking (change blindness)
People miss changes outside their focus. A total that updates at the top while they're at the bottom, or an error far from the field, goes unseen.
Applies to: Totals, errors and content that changes after an action.
BEH-34
The immediate benefit is shown (present bias)
People overvalue now and discount later. 'Protect your account' loses to 'Skip'; showing what they get today, or making it one tap, gets it done.
Applies to: Security setup, backups, savings, health and other long-term actions.
BEH-35
Effort estimates are honest (planning fallacy)
People underestimate time, and products do too. An estimate that's wrong by a lot breaks trust at the moment people are committing.
Applies to: Time and effort estimates: 'takes 2 minutes', step counts.
BEH-36
No insider knowledge needed (curse of knowledge)
The team knows what 'workspace', 'sync' or an acronym means; new users don't. Copy written from the inside leaves them guessing.
Applies to: Instructions, labels and empty states.
BEH-37
Errors are calm and don't blame (negativity bias)
Bad experiences weigh several times more than good ones. A harsh, blaming or alarming error colours the whole product; a calm one with a way forward doesn't.
Applies to: Errors, warnings and failure messages.
BEH-38
Showing the work is honest (labour illusion)
Seeing the steps being done makes waits feel worth it and raises trust. Fake steps or theatrical delays are deception that people eventually notice.
Applies to: Waits for search, AI answers and processing.
BEH-39
Friction is added where a mistake is expensive (positive friction)
Smooth is not always good. A typed confirmation, a review step or a short delay before an irreversible action prevents the errors people regret most.
Applies to: Irreversible, costly or shared actions.
BEH-40
Permission is asked in context, with the reason (just-in-time)
Asked at launch with no context, people refuse and rarely reconsider. Asked when the feature needs it, with what they get, most agree.
Applies to: Requests for location, camera, contacts, notifications and other permissions.
BEH-41
Alerts are reserved for what matters (alert fatigue)
Every badge competes for attention; when everything is urgent, people learn to ignore all of it, including what's important.
Applies to: Notifications, badges and red dots.
BEH-42
Plain language: short sentences, common words (processing fluency)
Easy-to-read text feels more true and trustworthy, and is understood by more people. Long, abstract or legalistic copy is skipped or misread.
Applies to: All copy.
BEH-43
People keep control of what's done for them (autonomy)
People resist what they don't choose. A way to see why, adjust or turn off a recommendation keeps them using it; forcing it drives them away.
Applies to: Personalisation, recommendations and AI features.
BEH-44
Feedback builds a sense of competence
People stay with what makes them feel capable. Specific, earned feedback on progress motivates; generic praise or constant streak pressure doesn't.
Applies to: Progress, achievements and feedback on skill.
BEH-45
Undo beats 'Are you sure?' (confirmation fatigue)
People click through confirmations on autopilot, so the dialog doesn't prevent the mistake. An undo after the fact actually does.
Applies to: Confirmation dialogs.
BEH-46
Loss warnings are honest and specific
'You'll lose everything' to stop a cancellation exploits loss aversion and sunk cost. Say exactly what is kept, what goes and when.
Applies to: Cancellation, downgrade and deletion flows.
BEH-47
No nagging after a 'no'
Asking again on every visit after someone declined wears them down rather than persuading them; it's a recognised dark pattern.
Applies to: Prompts, popups and upsells people already declined.
BEH-48
No disguised ads or bait and switch
Ads made to look like content, or a button that does something other than it says, deceive people into actions they didn't choose.
Applies to: Ads, sponsored content and buttons.
BEH-49
No forced action or privacy zuckering
Requiring an account, contacts or extra data to do something that doesn't need it, or defaulting to sharing more, takes what people didn't agree to give.
Applies to: Sign-ups, sharing and data collection.
BEH-50
No trick questions or double negatives
'Uncheck this box if you don't want to not receive offers' is built to be misread, and consent obtained that way isn't consent.
Applies to: Opt-in and opt-out checkboxes and toggles.
10 rules · the full guide
RTL
Right-to-left screens: Hebrew, Arabic, Persian. On by default when the screen has right-to-left text.
RTL-01
The layout mirrors: navigation, back and reading order start on the right
A left-to-right layout with right-to-left text makes people scan the wrong way and look for Back in the wrong corner.
Applies to: Screens in a right-to-left language.
RTL-02
Directional icons point the reading direction
A Next arrow pointing right on a right-to-left screen points backwards. Icons with no direction (play, check, clock) stay as they are.
Applies to: Arrows, chevrons, progress bars, sliders and steppers on right-to-left screens.
RTL-03
Mixed text keeps its order
Without correct direction, a brand name, a version number or a final period jumps to the wrong end and the sentence reads scrambled.
Applies to: Right-to-left text that contains Latin words, numbers, emails, links or punctuation.
RTL-04
Numbers and currency read correctly
Digits stay left to right inside right-to-left text; a currency sign on the wrong side or a reversed phone number makes the value wrong or untrustworthy.
Applies to: Prices, amounts, phone and card numbers on right-to-left screens.
RTL-05
Text aligns to the right edge
Right-to-left text aligned left leaves a ragged starting edge and reads as an unfinished translation.
Applies to: Paragraphs, labels and lists in a right-to-left language.
RTL-06
Fields type in the direction of their content
Name and address fields type right to left; email, URL, phone and code fields type left to right. The wrong direction scrambles what people enter.
Applies to: Inputs on right-to-left screens.
RTL-07
No leftover strings in another language
An English 'Cancel' or error message on a Hebrew screen reads as unfinished, and some people won't understand it.
Applies to: Buttons, labels, errors and empty states on a right-to-left screen.
RTL-08
Dates, times and units use the local format
03/04 means 3 April in Israel and 4 March in the US; the wrong format causes missed appointments and wrong orders.
Applies to: Dates, times and units on right-to-left screens.
RTL-09
The type is set for the script
Letter-spacing, all-caps styles, tight line height or a font without the script's glyphs breaks Hebrew and Arabic text, and Arabic letters must stay joined.
Applies to: Hebrew, Arabic and Persian text.
RTL-10
AI messages follow the direction of their own text
An English answer forced right to left, or a Hebrew answer forced left to right, is hard to read. In a right-to-left chat the user's bubbles sit on the left.
Applies to: Chats and AI output in a right-to-left product.
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