Combinatorial Idea Generation
Combine two or three existing things to land in territory no one has explored yet.
- Difficulty
- Starter
- Time to result
- ~days to results
- Steps
- 4
- Confidence
- 80%
Cortland Allen's technique for generating differentiated startup ideas is to take two or three existing concepts and mash them together, similar to how adding more words to a Google search collapses billions of results down to zero. A single concept ('email' or 'to-do list') is crowded; combining it with a second or third context ('email' + 'Facebook', or 'to-do list' + 'inbox') instantly produces a much smaller, often untouched space. Allen used this to generate Fmail (Gmail inside Facebook), Task Force (to-dos inside your inbox), and ultimately Indie Hackers (Hacker News-style startup discussions + mandatory revenue transparency).
Origin
Allen noticed that his and other early founders' most attention-grabbing projects were always simple combinations of two familiar things, and generalized it into a repeatable ideation technique.
Core principles
- 01A single concept has too much existing competition to stand out.
- 02Combining two or three concepts rapidly narrows the field toward true novelty.
- 03Novel combinations attract press and attention even when execution is simple.
- 04The technique works for products and for niche businesses alike.
How to run it
- 1
Pick a broad, well-known concept
Start with a familiar category or product type that already has proven demand (e.g., 'to-do list', 'email').
- 2
Pick a second (or third) context to merge it with
Choose another popular platform, format, or audience to combine with the first concept (e.g., 'inside Facebook', 'inside your inbox').
- 3
Test the combination for whitespace
Search for how crowded the combined idea already is — fewer existing examples signals more room to stand out.
Pro tip Think of it like a search query: more specific combined phrases return dramatically fewer (sometimes zero) existing results.
Watch out A whitespace idea still needs real demand — novelty alone isn't validation.
- 4
Ship a simple version fast
Build a minimal version of the combined idea quickly to capture attention before the space gets crowded.
In the wild
As a college junior with no web development experience, Allen built a simple app that mimicked Gmail's interface inside Facebook's new platform, combining two familiar products in a way nobody had done.
→ Despite being rejected from YC, the novelty of the combination earned coverage from multiple small tech publications.
Common mistakes
Combining without checking for real demand
A unique combination can still fail if the underlying problem isn't one people actually care about solving.
Is it for you?
Best for
Founders and builders brainstorming a new product idea in a seemingly crowded space.
Not ideal for
Deep technical or scientific innovation that requires solving a genuinely unsolved technical problem rather than remixing known concepts.
From the transcript
“one of the easiest ways you want to come up with any creative idea is just to take like two or three things and combine…”
“if you type like the dog into Google, you're gonna get like 10 billion results. But if you talk like the dog left, you're gonna…”
From the episode
Special: Acquired x Indie Hackers