Opportunities › Diagram and documentation tools for technical professionals › Proposed app
Plainline
Sketch fast, then polish the same diagram for formal docs. No redrawing.
- Score
- 47
- confidence 42
- Evidence
- 4
- items on the page
- Rivals
- 4
- named in sources
- First version
- 45 d
- estimate
- Type
- Desktop app
- PWA: runs in the browser, installs on Mac and Windows
- Market since
- 1992
- Mature market · AI estimate
ScreensConcept
Desktop app: Architects and engineers spend long stretches designing and editing diagrams for formal proposals and documents at a desk. Sample screens on a computer, in the proposed brand. Their numbers are sample data.
Payments design
Draft14 shapes
About this appAI proposal
Plainline is a diagram editor for architects and engineers. You start with loose, whiteboard-speed shapes and arrows. When the diagram must go into a proposal or formal document, you switch the same canvas to a clean style. Nothing is redrawn.
Each diagram can also be read and edited as text. Change the text and the canvas updates. Move a box by hand and the text keeps up. Unlike code-only tools, you place things where you want them, and layout is not forced on you.
It is for people who write proposals, design documents and architecture records and are tired of drawing everything twice.
- Tagline
- Draw it once. Use it everywhere.
- Voice
- PlainPreciseCalm
- Why this name
- Plain and line: rough ideas and clean documents share one set of lines. Two common words, easy to say.
In the first version
Members say which features they would use. It tells PWAS what people want; it changes no score.
One canvas, two looks
Toggle between a rough sketch style and a clean documentation style on the same diagram. Shapes, labels and links stay put.
No member yet
Snap-to-tidy
Select a messy area and align, space and straighten it in one step, so a quick sketch becomes presentable fast.
No member yet
Optional text definition
Open a text view of any diagram. Edit either side and the other follows. Keep the text in a repo if you like.
No member yet
Free placement
Pin any box anywhere. Auto-layout is a suggestion you can override, not a rule.
No member yet
Brand identityAI proposal
Check the name against trademark registers before using it.
Palette
#0F4C5CInk Teal · primary#F7F4ECPaper · surface#1E2328Graphite · text#E36414Signal Orange · accent#8DAA9DSage · data
Typography
Aa
Plainline
ABCDEFGHIJKLMNOPQRSTUVWXYZ 0123456789
Draw it once. Use it everywhere.
PricingAI proposal
The material gives no competitor prices or monetization. These tiers are a starting point to test, not based on evidence.
Free
Free
- Up to 5 diagrams
- Both looks
- PNG export
Pro
$8 a month
- Unlimited diagrams
- SVG and print-quality export
- Text view
- Offline sync
- Review links
Team
$14 a month
- Per user
- Shared libraries
- Shared shape sets
- Comment threads
- Version history
Would you pay Pro · $8 a month?
Your answer tells PWAS which prices people accept. It changes no score.
No answers yet.
What it could be worthEstimate
What a software business making this much sells for today, from real deals. Pick a monthly revenue.
If it makes
Worth about
$194,000
Sale range $132,000 to $263,000
$120,000 a year in revenue
From 87 software businesses listed and sold on Empire Flippers in the last year, revenue vetted by the broker: they sell for about 19× their monthly revenue, most between 13× and 26×.
Measured on profit, the middle deal is 32× monthly net profit: about 2.7 years of profit.
An estimate, not an offer or financial advice. A real price depends on profit, growth, churn, how much of the work is the owner's, and the buyer.
How it would growAI proposal
How the product would reach new customers through its own use, and how the first ones would be found. A plan to test, not a result.
- Built-in loop
- Shared outputs. Users send view-only links and exported diagrams in proposals and docs to reviewers and clients. The viewer shows a small made-with mark and a link to copy the diagram.
- Do they become customers?
- Reviewers mostly look once. Test whether reviewers who are also architects open a copy and start their own diagram, and how many do.
- First customers
- Solution architects at small consultancies who write client proposals and architecture documents with diagrams.
- Where to reach them
- Hacker News: Show a sketch-to-formal demo in the thread type where the demand was voiced, and invite testers.
- Architecture communities: Share templates for common patterns in forums and newsletters for architects.
- Open source docs: Offer free text-view diagrams for README and design docs to reach engineers.
- First milestone
- Ten architects use it for a real client document within a month, and five of them pay.
Why people already pay for this
- VerifiedHacker News post received 25 points and 16 comments
- Public claimUsers repeatedly sketch the same diagrams in quick tools and then have to redraw them in formal tools for documentation
- Public claimThere is demand for a tool that combines whiteboard-speed sketching with professional-quality output
- Public claimUsers want diagram authoring without the layout restrictions of code-based tools like Mermaid
Tech stack
Every proposal builds on the same PWA base, installable from the browser on any phone or computer. Dashed boxes are what this app adds.
- AppNext.js and TypeScript
- PWAManifest and service worker
- UITailwind CSS
- Data and authSupabase Postgres
- PaymentsStripe
- EmailResend
- HostingVercel
- This app · Canvas rendering2D canvas/SVG drawing library with hand-drawn styleNeeds a sketch look and a clean look from the same shape data.
- This app · Realtime syncCRDT library for shared editingKeeps text view, canvas and offline edits merging without conflicts.
RisksAI inference
- TechnicalTwo-way sync between free-placed canvas and text, while keeping hand-placed positions, is hard to get right.
- CommercialFree tools like Excalidraw and Draw.io are already used; people may not pay for fewer redraws alone.
- CommercialFormal documentation users may need Visio or Draw.io file import and export; without it switching is costly.
- DataArchitecture diagrams can be confidential; some teams will need self-hosting or strong privacy before trusting a new tool.
- PlatformLarge diagrams on phones and in the browser may be slow, and touch editing is limited on small screens.
Everything marked AI proposal or AI inference was written by a model from the evidence on the opportunity page. The proposed name must be checked against trademark registers before it is used.