Platform access level: Org Admins, Managers, and Writers (anyone who builds courses).
Arist delivers lessons over several delivery methods, and each one has its own rules for length, text formatting, images, and video. This reference collects every limit in one place so you can plan around them while you write. The editor keeps you inside the hard limits as you type and flags anything still to fix before you schedule the course, so knowing the numbers up front is about shaping a lesson rather than repairing one.
Images are the exception. Those checks cover your text and structure, not how a picture will render, and each delivery method handles what you upload a little differently, so an image can reach a learner cropped, as a still frame, or as a link instead of an embedded image. Follow the guidance in section 4, and preview a lesson on the delivery method you are sending over before it goes out. See Previewing and Testing Content.
1. Character limits
Each part of a lesson has its own limit. The editor shows a live counter under the field and stops accepting characters at the limit, so you can't overrun one by accident.
Field | Limit |
Lesson body | 1,200 characters |
Question and its answer choices combined, single-select | 300 characters |
Question and its answer choices combined, multi-select | 260 characters |
Response to learner (the feedback sent after an answer) | 800 characters |
Welcome message | 500 characters (your organization can request a different limit) |
Every line break counts as two characters against these totals, so count two for each one when you plan a body of several short paragraphs.
Note: Answer choices don't get their own separate limit. The question text and all of its choices share the combined budget, so a long question leaves less room for the answers. These are the limits; choosing between the question types is covered in Using Question Types and AI Assessment.
2. Text formatting by delivery method
Bold and italics use different syntax on each delivery method, so match your markup to where the course will deliver.
Delivery method | Bold | Italics | Also supports |
Microsoft Teams |
|
| Links as |
Arist Messenger |
|
| Links as |
Slack |
|
| Numbered and bulleted lists |
|
| Numbered and bulleted lists | |
SMS | Not supported | Not supported | Formatting is not supported for SMS messages |
3. Link shortening
A web address counts against the character limits in section 1 exactly like ordinary text, so one long URL can crowd out most of a lesson. The content editor's link shortener trades a long address for a compact link on Arist's own arist.link domain.
You open it with Actions > Shorten link in the content editor. What you paste can be any length, because what comes back is always that domain plus a short code. Start the address with http:// or https://.
For the walkthrough, including copying the finished link before you close the window, see Using the Content Editor.
4. Image guidelines
A few rules keep images sending properly, and none of them involves resizing anything yourself.
Nothing to arrange: A lesson's image sits in a fixed slot directly above the Body field, and neither the image nor the body can be dragged. Any extra media you add as a block below the body can be reordered among the other blocks.
Upload up to 5 MB per image: The editor accepts jpg, png, and gif files up to 5 MB, then automatically compresses each image until it's under 3 MB (600 KB for GIFs) while keeping a full-resolution copy. Arist enforces no pixel dimensions, though delivery methods render some sizes better than others.
Prefer landscape: Horizontal images render well everywhere. Vertical and square images eat vertical space and can overlap or stretch, which is why Arist's AI image tools generate at 16:9.
Name files simply: Keep file names under 20 characters, with no spaces or special characters. This matters most for SMS and MMS delivery.
Those rules cover the upload. Each delivery method then renders what it receives a little differently, and a few have their own ceilings worth designing around.
Delivery method | What to keep in mind |
SMS and MMS | 5 MB per message is a hard delivery limit, and carriers deliver most reliably under 600 KB per image. MMS reaches the US and Canada only, so learners elsewhere get a link in the message body instead. |
WhatsApp has no native GIF support, so Arist sends a GIF as a link to the image instead of an animation. The character budget in section 6 decides whether a still image embeds at all. | |
Aim for 200 to 500 KB per image, with the whole email under 1 MB. Design to a 600 to 650 px layout width, export at 2x for high-resolution screens, and keep the message at least 60% text so spam filters don't flag it. | |
Microsoft Teams | Cards cap images at 1024 x 1024 px and crop from the center, so anything wider can render incorrectly. An animated GIF may arrive as a single still frame. |
Slack | Effectively no size limit. To preview inline, an image needs to stay under 25,000 px on its longest side and under 45 million pixels in total. |
Arist Messenger | Images display up to 400 px tall, and up to 55% of the width on desktop or 90% on mobile. |
Important: An image is the one part of a lesson that can reach a learner in a form you did not choose. The editor's content checks do not look at how an image will render, so the guidance above will support in proper rendering, and a preview on the delivery method you are sending over is how you confirm it. See Previewing and Testing Content.
5. Video guidelines
You can add video to a lesson by uploading a file or linking a public platform, and learners see a preview above the message.
Upload directly: The editor accepts mp4, mov, wmv, and avi files up to 500 MB or 15 minutes, hosted on an Arist link. Its own recommendation is to keep videos under 5 minutes for the best learning experience.
Edit the preview: You can change an uploaded video's title (up to 240 characters) and pick its thumbnail frame in the content editor, which is exactly what learners see before they tap.
Link to a platform: YouTube, Vimeo, Loom, and Synthesia links preview reliably; other platforms aren't guaranteed to display well.
Synthesia videos don't report answers: If a Synthesia video includes its own interactive questions, a learner's answers inside that video aren't tracked back into Arist reporting. Use them for engagement, not for graded checks.
WhatsApp sends video as a link: Both uploaded and linked videos arrive on WhatsApp as a tappable link rather than embedded media.
Important: Uploaded videos are accessible to anyone with the link, no sign-in required, so avoid uploading content that must stay inside your organization.
6. WhatsApp character budget
WhatsApp is stricter than the editor about how much text can travel alongside an image. This one is a recommendation, not a limit: nothing stops you from going over, and the course still saves and delivers. The editor shows a warning banner with the length to aim for.
The banner appears when a lesson's body plus its first question's prompt go over a suggested combined length, and that length depends on the type of that first question:
First question in the lesson | Recommended combined length (body + question prompt) |
No question in the lesson | Under 1,020 characters |
Open-ended question | Under 1,000 characters |
Confidence lift survey | Under 1,000 characters |
Rating question | Under 980 characters |
Multiple choice, 2 or 3 answer options | Under 1,000 characters |
Multiple choice, 4 or 5 answer options | Under 990 characters |
Multiple choice, 6 to 8 answer options | Under 980 characters |
Every answer option you add to a multiple choice question reserves 4 more characters, and the editor rounds the figure down to the nearest 10, so it keeps stepping down past eight options. You never need to do this math yourself. The banner names the exact number for the lesson you're editing.
The recommendation exists to protect your images. Once the message WhatsApp actually sends reaches 1,024 characters, WhatsApp can no longer deliver the lesson's image inside the message, so learners receive a link to the image instead. The suggested lengths above sit just under that threshold, which leaves room for the question prompt without pushing the image out.
Note: The banner appears on any lesson over the suggested length, whichever delivery methods the course goes out on, which is why it opens with "If you plan to deliver this course over WhatsApp." If WhatsApp isn't one of your delivery methods, the banner doesn't apply to you.
When you translate a course, the Translate flow's SMS/WhatsApp Compliance toggle keeps translated text inside these lengths for you. See Translating an Existing Course.
Tip: To stay inside the WhatsApp budget, lean on bullet points, prefer short question formats, and move follow-up detail into the response-to-learner field instead of the lesson body.
7. Delivery rules on WhatsApp
Beyond character limits, WhatsApp restricts what can deliver at all.
Rule | What it means for you |
No nudges or surveys | WhatsApp delivers courses only |
No custom schedules | Use a Basic schedule; WhatsApp also never uses catch-up mode |
Delivery windows | A deliver-between window must span at least 5 hours |
Welcome message | Keep it short; learners reply START to begin. See Using System Keywords |
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Note: Need help at any point? Reach out to your Arist Customer Success contact, or email support@arist.co.

