Zovo Sequence Diagram

UML sequence diagrams from plain text lines.

Zovo Sequence Diagram turns a few lines of text into a UML sequence diagram. Write one statement per line: participants and actors, messages such as Web -> DB: Find user (sync), ->> (async) and --> (reply), self messages, notes over one or two participants, alt / else, loop and opt blocks, and activation bars. Each participant gets a lifeline, each message an arrow in the order you wrote it, and each block a frame around its messages. A line that does not follow the grammar is refused with its line number and the token, so nothing is guessed. The result states the counts and a check made on the final drawing: each message drawn once and in order, each frame holding the messages of its block and no others, and no two labels on top of each other. The PDF is Letter, A4 or Tabloid with text of at least 7 pt; long diagrams go on to more pages, cut between rows, with the participants repeated at the top of each page. Long message texts are wrapped to narrower lines so the diagram fits the paper. A diagram that is still too wide for the paper with text of at least 7 pt (about 11 participants with short names on Letter or A4, about 18 on Tabloid) gets no PDF, and the result says so; the SVG and CSV still have the whole diagram. You also get an SVG and a CSV of the messages in order. A second tool checks the text without drawing.

What it does

• Participants, actors, sync, async, reply and self messages, notes over one or two participants
• alt / else, loop and opt frames nested up to 8 levels, and activation bars
• Refuses a line outside the grammar with its line number and the token
• A check on the drawing: messages in order, frames holding their messages, no overlapping labels
• PDF (Letter, A4 or Tabloid) with participants repeated on each page, SVG and a CSV of messages
• A text check: counts, nesting, unbalanced activations and unused participants

Try asking

Limitations

• Up to 30 participants, 400 messages, 150 notes, 8 nesting levels and 60,000 characters
• Only the grammar on this page is read; features of other diagram languages outside it (par, critical, autonumber, -->> arrows, note left of) are refused with the line number
• Participant names are matched as written, including upper and lower case
• A diagram too wide for the paper with text of at least 7 pt (about 11 participants with short names on Letter or A4, about 18 on Tabloid) gets no PDF; the SVG and CSV still have it
• The PDF font covers Latin, Greek, Cyrillic and Vietnamese; Chinese, Japanese, Korean, Arabic, Hebrew and emoji show as ? in the PDF (the SVG and CSV keep them)
• Files of large diagrams are kept for 1 hour so the download links work, then deleted; download the files to keep them

Add it

Other MCP clients can connect to the same endpoint: https://sequence-diagram.zovo.one/mcp