Create diagram online free, with no signup wall

You can create diagram online free by opening the editor and pasting Mermaid, with no account and no install. In that sitting you get a live preview and a PNG at 1x with a small watermark. SVG is not part of the free export. JPG and PDF are not either. Those three are Pro.

I’m writing for the hour you actually have, not for a tour of the product. One sitting means: get a picture on screen, fix the obvious lie, and leave with a file you can put in a pull request or a scratch deck. Saving a library, a clean high-res PNG, and a vector export are the things that wait.

What the hour includes

The editor loads without a signup form in front of the text box. Paste a flowchart. The preview updates while you type. That loop is the product. I still meet people who export after every label change, as if the PNG were the compiler. It isn’t. The preview is the compiler. Export when someone who isn’t looking at the editor needs a bitmap.

You can edit anything you pasted. Rename a node, flip an edge, delete the box the sample didn’t earn. None of that asks for an account. I do my first pass logged out on purpose, because an account tempts me to save a draft I haven’t read. Reading is the work. Saving is a convenience for the second sitting.

Templates are in bounds for the free hour. Open one, duplicate the idea into the editor, and replace every noun before you trust it. A template with the original labels is somebody else’s system. I once left “Acme” on a box through a review because I was moving fast and the preview was green. Green meant the syntax parsed. It did not mean the box was ours. The template list is a shelf, not a suggestion that your architecture matches the sample.

PNG export works on the free plan. It is 1x, and it carries a small watermark. I use that file for myself: a screenshot in a personal note, a check that the theme didn’t eat a label. I don’t send it to a customer. The watermark is the plan being honest, and cropping it off in an image editor makes a fuzzy picture fuzzier. If the destination cares about a clean image, that is a different plan, and I’ll get to it.

What waits for an account, and what waits for Pro

An account is how you save diagrams on the site and share a link. The free plan’s sharing is basic, one public link, which is enough to drop a review URL in chat. It is not version history. On a free account the history I trust is still git, with the Mermaid fenced in the doc that changed. If you need the site to remember thirty old copies, you’re past the free hour.

The pricing page is the list I re-read when I mix the plans up. Starter is $6.99 a month. It keeps PNG, drops the watermark, and goes up to 4x, which is the file I want on a slide. Starter does not add SVG. I want that sentence to be boring and memorable. People hear “paid” and assume every format comes along. Starter’s export is still PNG.

Pro is $11.99 a month. JPG, SVG, and PDF show up there, and the PNG on Pro has no watermark. SVG is the one docs sites ask for, because it stays sharp and the text can remain selectable. If your pipeline says “export SVG” and you are on the free plan, the pipeline is asking for Pro. Don’t substitute a PNG and call it the same artifact. A docs build that only accepts SVG will not be satisfied by a watermarked bitmap, and it shouldn’t be. The PNG export page is the narrow tool for the bitmap path. Use it when PNG is actually the format you need. Don’t use it as a back door to a vector file. There isn’t one on the free plan.

AI sits in the free hour with a hard cap. Five uses total, for generate, edit, and fix together. They are not five per diagram and they are not five per day. I mention it here because “online free” gets read as “unlimited assistance.” It isn’t. If your hour is a paste-and-edit hour, you can spend zero of those uses. That’s the sitting I prefer when the chart already exists in a ticket.

A flowchart you can finish before you stand up

This is a feature-flag rollout I paste when I want a diagram done inside the hour. The decisions are real. The labels are short enough to fix quickly. Nothing in it requires an account to see.

flowchart TD
    pick[Pick the flag] --> dark{"Default off?"}
    dark -->|No| stop[Stop and fix the default]
    dark -->|Yes| staff[Enable for staff]
    staff --> bug{"Staff found a bug?"}
    bug -->|Yes| off[Turn the flag off]
    bug -->|No| percent[Raise the percent]
    percent --> full[Enable for everyone]

The first diamond is the one I used to skip. “We’ll remember to default it off” is not a step. It’s a hope. The chart makes the hope a gate, and the No path ends. It does not continue into staff enablement with a note that says “unless.” Notes don’t fail closed. Arrows do.

The bug diamond sends you to off, not to “debug in production at fifty percent.” I’ve drawn the brave version. We left the flag half-on over a weekend because the chart’s No path said “investigate” and investigate didn’t include a switch. The word investigate is a diary entry. Turn the flag off is an action. Use the action.

You can edit this in the free editor until the nouns match your flag system. If you don’t have a staff stage, delete staff and say what you do have. Don’t keep my stage because the picture looks balanced. Balance is not a rollout plan. I kept a staff stage on a mobile flag that had no staff build, and the QA lead asked which build. There wasn’t one. The rectangle was a habit from the previous chart.

A mind map of the sitting, so the hour doesn’t sprawl

A flowchart is the feature. A mind map is how I remember what the free hour contains, because people keep trying to do the Pro jobs in the same sitting and then they’re angry at a watermark. The map is not a process. Nothing here is in order except the way I clump the work.

mindmap
  root((Free hour))
    Paste
      Your text
      A template
    Edit
      Labels
      Arrows
    Preview
      Live
    Leave with
      The source
      A watermarked PNG

Paste, edit, preview, leave. The leave-with branch is the source plus an optional PNG. SVG is absent on purpose. If I put SVG on this map I’d be lying about the plan, and a mind map feels even more like a promise than a paragraph does. I won’t put “save a library” on it either. That’s the account’s job, in a later sitting, when the chart has survived one review.

Mind maps have no arrows. Don’t read Paste as “before” Edit as a sequence you’re required to follow. I often edit before I finish pasting, because the template’s second line is already wrong. The online flowchart notes are the roundup if you’re still deciding whether a text hour is the right kind of tool. This page assumes you already chose text and you want to know what $0 covers today.

Mistakes that blow the hour

Signing up before the first preview. The form costs a few minutes and buys nothing you need for the paste. I create the account when I want the diagram to live on the site. Until then the text can live in the pull request. The pull request was the archive anyway.

Asking the model to “make it free of errors” as use number one, with a prompt that says “diagram the rollout.” You’ll get a chart with a compliance team and a rollback service. Fixing that fiction is the rest of the hour, and you’ve spent a use. Type the diamonds you already know. The five uses are for a blank page with a real spec, not for a sentence you’re hoping will become a spec.

Exporting SVG in your head. You click export, you see PNG, you assume the other formats are hidden behind a caret. They aren’t hidden. They’re on Pro. I’ve watched a teammate click around for ten minutes looking for SVG on a free session. I should have said the sentence sooner. I’m saying it here. PNG now. SVG when the plan says Pro.

Treating the watermark as a bug and filing it in chat. It isn’t a bug. It’s the free bitmap. The free tool breakdown walks the same line from the other side, including what a free tool will not do as a drawing app. The diagram tool free notes sit next to that. If your actual problem is “I have a file and I only want to see it,” the viewer page is the closer fit. Don’t start a design session when you needed a render.

Comparing this hour to a different editor by memory. Open both, if you have both, and paste the same flag chart. The Mermaid Live alternative notes are the writeup for that comparison. I won’t invent a winner from a blog post I half remember. Paste the file you care about. See which preview matches the source you meant to keep.

A share link is a second sitting

I don’t create the public link in the free hour unless someone is waiting on the review. Saving wants an account. The free account’s sharing is one public link, and that link follows the current text. If you edit after you send it, the reviewer sees the edit. That’s what I want in a live review and what I don’t want if I promised a snapshot. Say which one you sent. “This will change if I fix the diamond” is a sentence that has saved me from a confused thread.

The link is also a bad archive. Free plans don’t keep a pile of versions on the site. If the review comment is “go back to the one I saw at 2pm,” and you edited at 2:10, you don’t have 2pm unless the text was in git. Paste the fence into the pull request before you send the link. The link is for people who will not open the pull request. The fence is for the people who will change it next week.

I’ve also sent the watermarked PNG and the link and forgotten they can disagree. The PNG was exported before the last diamond. The link was current. The reviewer commented on the PNG, because images are easier to quote in some chat apps. Now I name the file with the commit, or I don’t send the PNG at all. One artifact. The source.

Leave the sitting with the source

The artifact that matters is the Mermaid, in the doc or the ticket, fenced so the next person can change a label without redrawing. The watermarked PNG is a view. Views go stale. I date them in the filename if I must keep one, and I still lose the argument to a stale slide twice a year. The cure is the source in the repo, not a higher-resolution fossil.

If the hour produced a chart you’re willing to defend, stop. Don’t gold-plate it with another actor, another diamond, and a subgraph named “phase 2.” Phase 2 is how the free hour becomes a weekend. The flag chart above is enough to review a default-off policy. Add the percent schedule in prose under the figure if the schedule is a table. A table is allowed to be a table.

When you want that first paste, open the editor and put the flag chart in. Change staff to the stage you really run. Export a PNG only if someone needs the bitmap. If they need SVG, you’re done with the free hour and you’re looking at Pro, which is a fine outcome and a different sitting.