Pick Builderii if…
- Diagrams live next to screens and product flows
- You write diagrams in Mermaid
- PMs and designers edit the same boards
- You draw from Claude Code or Cursor
Eraser alternative
Technical diagrams by AI, next to the product they describe.
Eraser is a sharp tool for technical design docs. Builderii covers the diagrams engineers draw most, sequence, database, flowcharts and architecture, with an AI that writes them and a Mermaid pane that stays in sync, on the same board as the screens and flows the rest of the team works on.
Works in your browser · No card · Free while it’s new
In short
Builderii is an Eraser alternative for engineers who diagram systems: its AI draws sequence diagrams, flowcharts, database diagrams and architecture from a sentence and changes them in place, Mermaid stays in sync with the shapes, and SQL or Prisma becomes a database diagram. Wireframes, prototypes and workshops share the canvas. Eraser is the better pick for its own diagram-as-code language, docs-plus-diagrams files and cloud icon sets.
- Best for
- Engineers and PMs who want system diagrams next to the product work
- Eraser does better
- Its own diagram-as-code syntax, design docs with diagrams, cloud architecture icons
- Diagram as code
- Two-way Mermaid; SQL and Prisma for databases
- Price
- Free while it’s new, with every feature and 200 AI jobs a month
Why teams pick Builderii
Diagrams your whole team can read and change.
Sequence diagrams
Participants, lifelines and sync, async and reply messages from a prompt or a Mermaid paste.
Database diagrams
Paste SQL for Postgres, MySQL, SQLite or SQL Server, or Prisma models; export SQL back.
Two-way Mermaid
The Diagram as code pane keeps code and shapes in step; export Mermaid for READMEs.
AI that edits in place
Select a message or a table and ask for a change; Review AI changes shows what moved.
Architecture
Start from the serverless architecture template, light or dark.
From your AI assistant
Claude Code, Cursor and other MCP clients draw on your boards through 37 tools.
Side by side
Builderii and Eraser, side by side.
| Feature | Builderii | Eraser |
|---|---|---|
| AI technical diagrams | Sequence, database, flowcharts, sitemaps and more, changed in place | Yes |
| Diagram as code | Two-way Mermaid | Its own diagram-as-code syntax |
| SQL and Prisma to a database diagram | Yes, and SQL back out | Yes |
| Design docs | Rich-text docs on Home, and specs from flows | Docs and diagrams in one file |
| Wireframes and clickable prototypes | Built in | Not its focus |
| Price to start | Free, with every feature | A free plan with limits; paid plans |
Compared from each product’s public pages in October 2026; features change, so check before you decide. Product names are trademarks of their owners. Builderii isn’t affiliated with or endorsed by them.
Which to pick
Which one fits your team?
Pick Eraser if…
- You like its diagram-as-code language
- You write long technical design docs with diagrams inline
- You need its cloud architecture icon sets
Questions
Good questions.
Does Builderii support diagram as code?
Yes, with Mermaid: paste flowchart, sequence or mind map code for native shapes, or open the Diagram as code pane (⇧⌘M) to edit code and shapes together.
Can I bring SQL or Prisma?
Paste or import SQL CREATE TABLE statements or Prisma models for a database diagram, and export SQL back for the page or the selection.
Can Claude Code draw diagrams in Builderii?
Yes. Install the Claude Code plugin or add Builderii’s MCP server, and ask for a diagram of your code; it lands on your board.
Is Builderii free?
Yes. Builderii is free while it’s new, with every feature on and 200 AI jobs a month per person. Viewers and commenters will always be free, and paid plans will publish their AI allowances.
Keep reading
More ways to use Builderii.
What do you want to build?
Start with a prompt, a template or a blank board. It’s free.