Comparison
Wavelength
MermaidMap the process on the call, then export it as Mermaid
Mermaid, PlantUML, D2 and Graphviz are free, version controlled, and render straight out of a repository. They share one assumption: you can already describe the process precisely enough to type it.
During discovery you cannot. You are learning the process in fragments from someone who has never had to explain it in order before, and every second spent on syntax is a second not spent listening. That gap is what Wavelength is for. And when the flow is right, Wavelength gives you the Mermaid.
The demo needs no account. The free plan needs no card.
The actual difference
| Diagram as code |  Wavelength | |
|---|---|---|
| Input | Syntax you type | Speech, or a pasted transcript |
| What it assumes | You know the flow well enough to write it down | You are hearing it for the first time |
| Where it lives | A file in your repository | A hosted flow on your account |
| Version control | Native. Diffs in a pull request | Version history and restore on Pro |
| Layout | The rendering engine decides | Auto-laid out, then draggable by hand |
| Shows its uncertainty | Not applicable, you typed it | Yes, inferred links render dashed amber until confirmed |
| Usable live in a meeting | Only if you can type it faster than they talk | Yes, that is the design point |
| Cost | Free and open source | Free tier, then $4.99 per month for one user. Teams: Pro at $9.99 per seat. |
Mermaid, PlantUML, D2 and Graphviz are free and open source. Commercial hosted editors built on top of them are priced separately. Cost is not the deciding factor here.
What changes when you switch to Wavelength
Describe the process on the call, and Wavelength draws the flow. Copy the Mermaid code when the flow is confirmed. See Mermaid import and export.
Where typing costs you the meeting
Someone says this on a discovery call:
"Orders land in Postgres. Fivetran copies them to BigQuery every hour. dbt runs the models, and if the tests fail, the on-call analyst gets a Slack alert. If they pass, Looker refreshes the dashboard."
To turn that into Mermaid you have to make four decisions before you type a character: which diagram type, which node ids, which of those things are decisions rather than steps, and which ones are data stores. Every one of those decisions is thinking you are doing instead of listening.
flowchart TD
PG[(Postgres)] --> FT[Fivetran]
FT -->|every hour| BQ[(BigQuery)]
BQ --> dbt[dbt]
dbt --> T{Tests pass?}
T -->|No| Slack[Slack alert to on-call analyst]
T -->|Yes| Looker[Looker dashboard]
That is not hard to write. It is hard to write at conversational speed while you also run the call, and the code does not record which links you inferred.
Wavelength takes the sentence and produces the same structure without the four decisions: data stores, systems, the test decision, and the hourly timing on the link. Then you correct it by voice, by prompt, by right-click, or by hand.
The dashed amber lines
Code has no notion of confidence. Every edge you type reads as fact. Wavelength draws inferred connections dashed and amber, so before you send the diagram to a customer you know exactly which two or three links to confirm out loud.
From the call to the repository
Capture live in Wavelength while the process is being described, correct it in the room, and get agreement. Then copy the flow as Mermaid, or open it in Mermaid Live, and commit it next to the code. The diagram in the repository starts from a map the business already confirmed.
Wavelength also imports Mermaid files, so an existing diagram can come back for the next discovery call. There is no PlantUML export yet. If PlantUML export matters to you, tell us.
Common questions
Could I not just ask an LLM to write the Mermaid for me?
You can, and for a tidy paragraph it works. Two things are different here. The diagram appears while the conversation is happening rather than after it, so the other person can correct it in the room. And inferred edges are marked as inferred rather than silently becoming fact, which is the failure mode of pasting a transcript into a chat window and trusting the output.
Does Wavelength do sequence diagrams or class diagrams?
No. Wavelength draws process and data flows, using 8 node types, swimlanes, and cloud icons. That focus is what lets it place each shape from speech in real time.
What if the meeting already happened?
Paste the transcript and you get the same diagram. See transcript to flowchart.
Can I edit the layout?
Yes. Nodes auto-arrange and then drag freely, and connections can be reversed or reshaped by clicking them. This is one of the more common complaints about code-rendered diagrams, where the engine's layout is what you get.
Other comparisons
See Wavelength vs Lucidchart, Wavelength vs Miro, Wavelength vs Visio, and the comparison index.
Try it before you decide
Describe a process you already know well enough to write as Mermaid, and compare what comes back. That is the fairest test of whether the capture step is worth anything to you.
7 days of Pro. No card.