Splitline by SEAI

02 / Splitline field manual

Get started on your Mac

Install the universal app and choose the opening method that matches how you plan to save.

Updated

Check requirements

Splitline supports macOS 12 or later on Apple silicon and Intel Macs. Production downloads are universal, Developer ID signed, notarized by Apple, and checked before publication.

You can open:

  • arbitrary JSON documents in .json;
  • newline-delimited row data in .jsonl; and
  • delimited row data in .csv and .tsv.

All text input must be valid UTF-8. For current build and update details, see Releases.

Install Splitline

  1. Get the DMG

    Splitline has not launched yet. Join the waitlist and we will send Splitline.dmg download details at launch.

  2. Move Splitline to Applications

    Open the DMG, drag Splitline into Applications, then eject the disk image.

  3. Launch it once

    Open Splitline from Applications. This also lets macOS register it as a viewer for the supported file types.

Updates stay under your control.

Splitline can show a notice when a newer stable release is available. It never downloads or installs an update silently; you start the download and replace the app manually.

Licensing

Splitline takes a one-time license, for one person, with lifetime use and updates. It is not a subscription.

Splitline has not launched yet, so the terms are announced at launch — join the waitlist to hear them first. Checkout, activation, recovery, and refund terms are maintained on the License and Refunds pages.

Open files

Choose the path based on what you are doing:

Method Best for Save behavior for row datasets
Double-click or Open With → Splitline in Finder Opening one real file quickly A complete row file is eligible for in-place Save.
Add files Choosing several files from inside Splitline On macOS, edits leave through Export copy and a native Save dialog.
Open folder Loading related train, validation, and test files together On macOS, edited files export as copies.
Drag and drop Adding files to the running workspace On macOS, edited files export as copies.

Adding your first real files replaces the demo. A Finder file opened while Splitline is already running joins the same file rail and becomes active. macOS sends one supported regular file per open request; Splitline does not receive general filesystem access.

Finder controls in-place access.

Only a complete row dataset opened through the operating system’s file-open event can use in-place Save. JSON documents and partial row loads never enter that save allowlist.

Use Splitline from Finder

Splitline owns its .jsonl document type, but registers only as an alternate viewer for JSON, CSV, and TSV so installing it does not replace your editor or spreadsheet app.

To open a file once, Control-click it and choose Open With → Splitline. To make Splitline the default for that extension, select a file in Finder, choose File → Get Info, select Splitline under Open with, and choose Change All.

Continue with Row datasets for JSONL, CSV, or TSV, or JSON documents for arbitrary JSON.

Guide screenshot · full resolution