Double Bubble

01 · Section

Why it works

Most ideas die because they're described in isolation. 'A note-taking app for builders' tells you nothing — it could be Notion, it could be Bear, it could be a half-finished thing on someone's GitHub. 'Notes, but the notes write themselves into a launch plan' tells you everything, because the second version implicitly compares to Notion and immediately announces what's different. Double Bubble forces that comparison out into the open before you commit. The brain only understands new things by contrast — the second you give it a comparison anchor, every detail snaps into focus. Skipping this step is why most solo-builder ideas get described in three different ways across three different conversations and never land.

02 · Section

How to draw it

Two circles. One per idea. Where they overlap, list every trait they share — auth, search, dark mode, mobile app, the table stakes. On the outside of each circle, list the traits that only belong to that idea. The longer your right-side outside list, the sharper the differentiation. The diagram looks like this: ```text ┌───────────────┐ ┌───────────────┐ │ ONLY THEM │ SHARED │ ONLY ME │ │ │ ╭─────╮ │ │ │ - feature A │ │ auth │ │ - feature 1 │ │ - feature B │ │search│ │ - feature 2 │ │ - feature C │ │ sync │ │ - feature 3 │ │ │ ╰─────╯ │ │ └───────────────┘ └───────────────┘ ``` Draw it on paper, in Figma, on a napkin — doesn't matter. The diagram is a thinking tool, not an artifact. You'll throw it away in 20 minutes.

• Left circle: the obvious comparison (Notion, Linear, ChatGPT, Substack — the thing your user would name first).
• Right circle: your idea.
• Middle: the table stakes you both share — auth, search, sync, dark mode, mobile.
• Outside left: what they have that you don't (and don't need to build).
• Outside right: the three to five traits that only you have. This is your homepage headline.
• Aim for at least three items on the right outside. Two means the idea isn't sharp yet.

03 · Section

Worked example — a journaling app vs. Notion

Let's run one end to end. The idea: a journaling app called Inkling that turns daily entries into a private year-end book. The obvious comparison is Notion, because that's where most people would default to journaling today. **SHARED (the middle):** rich text editor, mobile sync, search across entries, dark mode, password protection, image upload. **ONLY NOTION (left outside):** databases, kanban boards, public sharing, team workspaces, AI assistant, templates marketplace, embeds, hierarchical pages, slash commands. **ONLY INKLING (right outside):** prompts a question every morning at 7am, automatically formats the year as a printed book in December, never has a public sharing feature (private by design), uses warm sepia paper aesthetic instead of clinical white, has a single 'today' view with no sidebar. The right-side list is the headline factory. Three candidates fall out: - 'Journaling that ends in a book on your shelf, not another doc to manage.' - 'A daily prompt, a private page, a printed year. That's it.' - 'Notion is for teams. Inkling is for you, alone, at 7am.' The last one is the strongest because it names the comparison directly and makes a values claim. That headline came out of the bubble in under ten minutes.

04 · Section

Three more case studies

The same move applied to three more ideas, condensed. Notice how the headline always comes from the right-outside list, never from the middle.

• **Kids piano app vs. Simply Piano.** Only us: parent-and-child mode where they play together, no streaks or gamification, songs are real classical pieces not pop covers, sessions cap at 15 minutes by design. Headline: 'A piano practice app that ends after 15 minutes — because that's all a 9-year-old needs.'
• **Developer search tool vs. Google.** Only us: searches your own past code and Stack Overflow answers together, results ranked by 'has this person actually shipped this', no ads ever, terminal-first interface. Headline: 'Google for code, minus everyone who's never shipped any.'
• **Recipe app vs. AllRecipes.** Only us: every recipe written by one chef (not crowd-sourced), no ads, no story before the recipe, scaled to exact pantry inventory you've added. Headline: 'One chef. No ads. No life story. Just the recipe, scaled to what's in your fridge.'
• Pattern across all three: the headline names the comparison and the refusal in the same line. That's the move.

05 · Section

Common pitfalls

Four ways the exercise fails. If your bubble feels mushy, you've probably hit one of these.

• Comparing to a category, not a product. 'My idea vs. project management tools' is too vague. 'My idea vs. Linear' forces real specifics.
• Listing aspirations as 'only me'. 'Better UX' isn't a trait. 'A single 15-minute timer that hard-locks the session' is.
• Forgetting the middle. If you skip the shared list you'll over-claim differentiation. The middle is what keeps you honest about what you still have to build.
• Picking a comparison nobody knows. Comparing to a niche app means your headline doesn't land — pick the household name even if it's not the closest competitor.
• Right-outside list too long. If you have ten things only you do, you're describing five products. Cut it to three. Those become the headline.

06 · Section

Variations

Three ways to evolve the move when the basic two-circle version isn't enough.

• **Triple Bubble** — three circles, one per major competitor, with all overlaps mapped. Useful when there's no single obvious comparison (e.g. a new social app could be compared to Twitter, Instagram, and Discord at once). The center triple-overlap is the table stakes for the whole category.
• **Bubble-of-Bubbles** — instead of comparing whole products, compare a single feature across both. 'Search in Notion vs. search in my idea' — go deep on one comparison and you'll often find that the entire product idea hides inside one feature.
• **Anti-Bubble** — skip the right circle entirely and just list everything you refuse to build. The refusal list is the brand. Brands like Basecamp and Bear have been built almost entirely from anti-bubbles.

07 · Section

When to use it

Run a Double Bubble before you name the product. Before you write the homepage. Before you scope the MVP. Before you tell your friends what you're building. If you can't fill the right-side outside list with at least three real, specific things, the idea isn't sharp enough yet — go back to the bubble before you go forward to the code. Most builders do this once. Pros do it every time they add a major feature, because every new feature is a small new product that deserves its own bubble.

08 · Section

Paste this into Lovable

Two prompts. The first runs a standard Double Bubble. The second runs the Triple Bubble variation when you have multiple competitors and need to triangulate.

You are a product strategist. I'm going to give you my product idea and the obvious comparison. Run a Double Bubble:

1. SHARED — list 5 traits both products have (the table stakes).
2. ONLY THEM — list 5 traits the comparison has that I should explicitly NOT build.
3. ONLY ME — list 5 traits that only my product has. These become my homepage headline candidates.

Then write three one-line headlines based on the ONLY ME list. Each headline must name the comparison and the refusal in the same line.

My idea: [paste your idea]
Obvious comparison: [paste the competitor]

09 · Section

Triple Bubble prompt

Use this when there are three obvious comparisons and you need to find the gap between all of them.

You are a product strategist. I'm giving you my product idea and three competitors. Run a Triple Bubble:

1. CENTER (all three share) — list the 5 category table stakes.
2. ONLY A, ONLY B, ONLY C — list 3 traits unique to each competitor.
3. ONLY ME — list 5 traits that none of A, B, or C have but my product does.
4. THE GAP — name the single biggest unfilled space across A, B, and C that my product could own.

Then write three one-line headlines based on THE GAP.

My idea: [paste]
Competitor A: [paste]
Competitor B: [paste]
Competitor C: [paste]