01 — A markdown reader for technical work

A reader,
not a viewer.

Sigla renders the diagrams, math, and code technical documents are made of, with room to write in the margins.

Sigla is a markdown reader for technical work — RFCs, design docs, postmortems, runbooks, LLM output. It renders the formats those documents use: Mermaid, PlantUML, Vega-Lite, math, code, frontmatter you can read.

Reading is only half of it. Highlight a phrase, attach a note — your annotations live in a sidecar that never touches the source. Export wraps those notes and the document into a prompt template you control, ready for any LLM.

Sigla rendering a design document with an embedded sequence diagram

Sigla in dark mode showing a postmortem with two inline annotations and a code block — Sigla in dark mode, showing a postmortem with two inline annotations and a code block.

02 — Render

Render diagrams, charts, math, code.

Diagrams and charts render inline. KaTeX math. Syntax-highlighted code across thirty-plus languages. Frontmatter rendered as a real panel, not dropped. Link integrity checked across the folder.

03 — Annotate

Highlight a phrase, attach a note.

Comments live in a sidecar file next to the document; the source markdown stays untouched. Marginalia while you read, or questions to answer later.

04 — Export to LLM

Export the document with your questions attached.

Every comment is anchored to a phrase in the source. ⌘⇧E packages the document and all annotations into one XML payload — ready to drop into whichever LLM you use.

<document path="./postmortem-2026-05-12.md">
  <content>
    ## 14:22 UTC — Database failover

    Primary `db-east-1` lost network at 14:22 UTC. Failover
    to `db-east-2` completed at 14:31. Downtime: 9 minutes.

    SLA window was breached by 4 minutes.
  </content>
  <comments>
    <comment anchor="Failover to `db-east-2` completed at 14:31">
      Was the failover automatic or did someone trigger it?
      The runbook says auto, the timeline reads manual.
    </comment>
    <comment anchor="SLA window was breached by 4 minutes">
      Why didn't auto-failover trip at the 4-minute mark?
      Our SLA target was 5.
    </comment>
  </comments>
</document>

Every comment ships with the exact phrase it's anchored to — so the question and the line it's about travel together.

05 — Get Sigla

Give Sigla a try.

Download for Mac

Direct download · latest release · drag to Applications

Or install with Homebrew

brew install --cask slantedt/tap/sigla

Installs the cask, sets up brew upgrade for future versions.

macOS 14 Sonoma or later · Apple Silicon and Intel · universal binary

v1.0.0 · Released June 13, 2026

See pricing