Social Media Character Limits

This guide summarizes the most relevant text limits for each social network supported by Upload-Post. Keep these constraints in mind when building payloads so posts are accepted without truncation.

Platform-Specific Character Limits

Facebook Character Limits

Property	Description
post	63,206 characters maximum
title	Reels title – 255 characters maximum

Instagram Character Limits

Property	Description
post	2,200 characters maximum
altText	1,000 characters maximum per image
comment	2,196 characters maximum

LinkedIn Character Limits

Property	Description
post	3,000 characters maximum
title	400 characters maximum
comment	1,250 characters maximum

TikTok Character Limits

Property	Description
post	2,200 characters maximum

Pinterest Character Limits

Property	Description
post	500 characters maximum
title	100 characters maximum
link	2,048 characters maximum
altText	500 characters maximum

Reddit Character Limits

Property	Description
post	5,000 characters maximum
title	300 characters maximum
comment	10,000 characters maximum

Threads Character Limits

Property	Description
post	500 characters maximum

X (Twitter) Character Limits

Property	Description
post	280 characters maximum
post (Premium)	25,000 characters maximum for Premium and Premium Plus accounts
altText	1,000 characters maximum per image
subTitleName	150 characters maximum

Bluesky Character Limits

Property	Description
post	300 characters maximum
images	Up to 4 images per post
altText	Supported

YouTube Character Limits

Property	Description
post	5,000 characters maximum
youTubeOptions > title	100 characters maximum
youTubeOptions > tags	500 characters total, 2+ characters each
youTubeOptions > subTitleName	150 characters maximum

Content Restrictions

Banned Hashtags

Upload-Post validates content against a list of prohibited hashtags before posting to Instagram. Posts containing any of these hashtags will be rejected with a validation error. The complete list of banned hashtags includes:

A: anorexia, alone, a$$, antivax, abdl, addmysc, adulting, always, armparty, asiagirl

B: beautyblogger, bikinibody, boho, blogladrona, brain, besties, bikinibod

C: costumes, curvygirls, cancer

D: date, dating, desk, dm

E: elevator, edm, endme

F: followtrain, followtrains

G: graffitiigers, girlsonly, gloves

H: hardworkpaysoff, happythanksgiving, humpday, hustler, hotgirls

I: iphonegraphy, italiano, ifb

K: kansas, killingit, kissing, kill, killme, killyourself, kys

M: master, models, mustfollow, milf, midget

N: nasty, newyearsday

P: petite, petitegirls, pushups, payme

S: saltwater, shit, shower, single, singlelife, skype, snap, snapchat, snapchatme, snowstorm, sopretty, stranger, streetphoto, sunbathing, swole, suicide, suicideawareness

T: tag4like, tanlines, teens, teen, thought, todayimwearing

U: undies, unbalanced

V: valentinesday

W: workflow

Y: youngmodel, yolo

If your content includes any of these hashtags, remove them before submitting your request to avoid validation errors.

API Considerations

• Upload-Post validates payload sizes before sending them to social networks whenever limits are known. Requests that exceed the documented limits return a validation error.
• Some platforms might truncate overlong text instead of rejecting it (Meta products and YouTube occasionally do this). Inspect the per-platform response inside results to confirm the final content.
• For channels with strict limits such as X, consider shortening URLs in your application prior to calling the Upload-Post API.

Updates and Changes

Social networks regularly adjust their limits. We keep this page aligned with the latest behavior we observe in production, but you should also:

• Check Upload-Post API responses for detailed error messages about rejected posts.
• Subscribe to our release notes for platform updates.
• Revisit this reference periodically, especially before large content campaigns.