{"id":1557,"date":"2025-02-26T01:06:00","date_gmt":"2025-02-26T01:06:00","guid":{"rendered":"https:\/\/f13.kr\/sooha\/?post_type=project&p=1557"},"modified":"2026-02-19T20:50:24","modified_gmt":"2026-02-19T20:50:24","slug":"expense-manager","status":"publish","type":"project","link":"https:\/\/www.sooha.kim\/index.php\/project\/expense-manager\/","title":{"rendered":"Spendable"},"content":{"rendered":"\n
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Spendable<\/strong> reframes \u201cmy money\u201d into real
spendable money \u2014 grounded in behavioral psychology.<\/p>\n\n\n\n

I redesigned the default money metric so users instantly see
what they can actually spend after fixed costs and goals.<\/p>\n<\/div>\n\n\n\n

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Type<\/strong><\/p>\n\n\n\n

Team-built iOS app
(development program project)<\/p>\n<\/div>\n<\/div>\n\n\n\n

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Role<\/strong><\/p>\n\n\n\n

UX\/UI
Interaction design
Contributed to Swift implementation<\/p>\n<\/div>\n<\/div>\n\n\n\n

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Tools<\/strong><\/p>\n\n\n\n

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Concept<\/p>\n\n\n\n

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Designing Spendable Balance<\/h2>\n\n\n\n
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A future-aware money metric that makes
\u201csafe to spend\u201d visible at a glance.<\/p>\n<\/div>\n\n\n\n

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Spendable Balance is the number designed for decisions<\/strong>, not tracking.<\/p>\n<\/div>\n\n\n\n

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It shows how much money is actually safe to spend<\/strong> after fixed costs and goal allocations are accounted for.<\/p>\n\n\n\n

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Problem<\/p>\n\n\n\n

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Most people don\u2019t overspend.
They misread their money.<\/h2>\n\n\n\n
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Account balance looks spendable,
but most of it is already committed.<\/p>\n<\/div>\n\n\n\n

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So I changed the default number.
By making Spendable Balance the primary metric, budgeting shifts from reactive logging to proactive control.<\/p>\n\n\n\n

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Moment Map<\/p>\n\n\n\n

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Where budgeting breaks<\/h2>\n\n\n\n
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Three moments where a misleading balance
turns into overspending or avoidance.<\/p>\n<\/div>\n\n\n\n

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UX strategy<\/p>\n\n\n\n

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4 mechanisms behind
Spendable Balance<\/h2>\n\n\n\n
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Behavioral psychology turned into four UX mechanisms
\u2014 built for the moments where budgeting breaks.<\/p>\n<\/div>\n\n\n\n

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Default Metric Reframe<\/h6>\n\n\n\n

Give Your Brain a Break
\u2014Let Me Handle It<\/h4>\n\n\n\n

Prospective Processing & Reducing Cognitive Load<\/h6>\n\n\n\n

Uncertainty creates mental load. By showing Spendable Balance after fixed costs and goals, the app removes mental math and makes spending decisions clearer.<\/p>\n<\/div><\/div>\n\n\n\n

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Your Brain Makes Thousands of Decisions a Day\u2014Let\u2019s Cut That Down.<\/h4>\n\n\n\n

Preventing Decision Fatigue<\/h6>\n\n\n\n

Fewer small money decisions means fewer chances for impulse spending. By locking fixed expenses upfront, the app turns essentials into non-negotiables\u2014reducing decision load by design.<\/p>\n<\/div>

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What If Hitting Your Savings Goal Felt Like a Shopping Spree<\/h4>\n\n\n\n

Reward System & Dopamine Regulation<\/h6>\n\n\n\n

Expense logging is reactive and often feels like punishment. Goals create anticipation and visible progress, making saving feel like a rewarding loop instead of deprivation.<\/p>\n<\/div><\/div>\n\n\n\n

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Spending Feels Different When You See It as Losing<\/h4>\n\n\n\n

Loss Aversion & Psychological Sense of Control<\/h6>\n\n\n\n

When money is allocated to goals first, spending is no longer \u201cusing leftover money.\u201d It becomes \u201ctaking away progress,\u201d which people feel more strongly and naturally try to avoid. This makes trade-offs clearer and supports better self-control without guilt.<\/p>\n<\/div>

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Proof of UX<\/p>\n\n\n\n

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How It Works in Real Life<\/h2>\n\n\n\n
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Three real-life flows that demonstrate
the mechanisms in action.<\/p>\n<\/div>\n\n\n\n

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Flow 1 \u2014 Setup (2 minutes)<\/p>\n\n\n\n

Goal: Turn essentials into non-decisions and
make \u201cavailable to spend\u201d instantly clear.<\/h4>\n\n\n\n

Mechanisms: Reframe \u00b7 Pre-commit \u00b7 Reward<\/p>\n<\/div>\n\n\n\n

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Add income
(starting point)<\/strong><\/p>\n<\/div>\n\n\n\n

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Set fixed expenses (weekly\/monthly\/date) \u2192 locked<\/strong><\/p>\n<\/div>\n\n\n\n

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Create goals + allocate amounts<\/strong><\/p>\n<\/div>\n\n\n\n

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Land on Home \u2192 Spendable Balance + combined goal progress<\/strong><\/p>\n<\/div>\n<\/div>\n\n\n\n

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Flow 1 \u2014 Purchase moment (10 seconds)<\/p>\n\n\n\n

Goal: Add a gentle pause before spending by
making trade-offs visible.<\/h4>\n\n\n\n

Mechanisms: Reframe \u00b7 Loss-aware feedback \u00b7 Reward<\/p>\n<\/div>\n\n\n\n

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From Home, tap to add an expense<\/strong><\/p>\n<\/div>\n\n\n\n

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Enter amount\/category (quick entry)<\/strong><\/p>\n<\/div>\n\n\n\n

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Preview impact (Spendable decreases \/ goal progress drops)<\/strong><\/p>\n<\/div>\n\n\n\n

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Confirm \u2192 updated balance + progress<\/strong><\/p>\n<\/div>\n<\/div>\n\n\n\n

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Learnings + Next bets<\/p>\n\n\n\n

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What I learned
and what I\u2019d build next<\/h2>\n\n\n\n
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Key takeaways from designing Spendable Balance,
plus the next experiments to reduce friction and strengthen the habit loop.<\/p>\n<\/div>\n\n\n\n

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The default number shapes behavior.<\/h5>\n\n\n\n

Changing the primary metric changed how users interpreted \u201cmy money\u201d in daily decisions.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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Friction is the real enemy of budgeting.<\/h5>\n\n\n\n

Habit breaks don\u2019t come from lack of intent, but from effort at the wrong moment.<\/p>\n<\/div>\n<\/div>\n\n\n\n

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The default number shapes behavior.<\/h5>\n\n\n\n

Visible goal progress can motivate better than reactive logging, as long as feedback stays neutral.<\/p>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

Product \u00b7 UX \u00b7 Development<\/p>\n","protected":false},"featured_media":2443,"template":"","meta":{"inline_featured_image":false},"project-category":[15],"class_list":["post-1557","project","type-project","status-publish","has-post-thumbnail","hentry","has-content"],"_links":{"self":[{"href":"https:\/\/www.sooha.kim\/index.php\/wp-json\/wp\/v2\/project\/1557","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.sooha.kim\/index.php\/wp-json\/wp\/v2\/project"}],"about":[{"href":"https:\/\/www.sooha.kim\/index.php\/wp-json\/wp\/v2\/types\/project"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.sooha.kim\/index.php\/wp-json\/wp\/v2\/media\/2443"}],"wp:attachment":[{"href":"https:\/\/www.sooha.kim\/index.php\/wp-json\/wp\/v2\/media?parent=1557"}],"wp:term":[{"taxonomy":"project-category","embeddable":true,"href":"https:\/\/www.sooha.kim\/index.php\/wp-json\/wp\/v2\/project-category?post=1557"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}