August 11, 2026
Boxes, arrows, and budget battles
Show HN: Line9 - a Mermaid rendering engine with its own layout
This diagram tool wowed people, then the price tag walked in and killed the vibe
TLDR: Line9 launched as a new tool for making Mermaid diagrams look better, and commenters agreed the problem it tackles is very real. But the discussion instantly turned into a pricing fight, with many saying the cost is too high and others pointing out Mermaid may already have a decent built-in alternative.
A new project called Line9 showed up promising prettier, smarter diagram layouts for Mermaid, the text-based chart tool people use to turn plain writing into flowcharts. On paper, that sounds like catnip for anyone who has ever watched their boxes and arrows turn into a tangled mess. And sure enough, the first wave of reaction was basically: finally, someone is fixing Mermaid’s messiest habit. One commenter flat-out said it solves their “biggest gripe” with Mermaid.
But this Show HN thread didn’t stay in honeymoon mode for long, because the real villain of the story quickly arrived: pricing. Multiple commenters took one look at the cost and went from curious to ice-cold. The mood was less “shut up and take my money” and more “absolutely not, procurement will laugh me out of the building.” One person compared it to Lucidchart’s lower monthly price, while another said there was no way their company would ever approve $120 per seat per year for something that has to fit into existing office tools.
Then came the classic internet split-screen. Some people were fascinated by the hard problem of arranging diagrams neatly and wanted the creator to spill the secrets. Others jumped in with a plot twist: Mermaid already has an alternate layout option, elk, and several readers treated that like the comments-section equivalent of yelling, “Guys, there’s already one in the garage!” So the vibe is clear: cool idea, real need, brutal price debate, and a side quest about whether the built-in option already does enough.
Key Points
- •Line9 is presented as a Mermaid rendering engine with its own layout system.
- •The showcased example is a 'Parcel Delivery' flowchart rendered with the boardroom theme and left-to-right orientation.
- •The flowchart models delivery steps and decision branches such as address verification, recipient availability, damage handling, redelivery, collection, and return to sender.
- •The diagram source includes node class assignments for groups such as gates, artifacts, and ending states.
- •The interface provides actions including copying source, downloading or publishing output, copying links, reporting renders, and accessing the line9 CLI and Pro offering.