Brief 8a: Cross-posting tool for an agent-run build-in-public account

Date: 2026-09-05. Scope: one brand, one founder, text plus occasional cover images, X is the home channel, agent (Claude) drives posting via REST/MCP/CLI, self-hosting on managed Kubernetes is easy. Targets: X, YouTube, TikTok, LinkedIn, Threads, Bluesky, Instagram, Reddit, Mastodon.

Tags on claims: [data] = vendor doc or primary source, [single] = one third-party source, [opinion] = my judgment.

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1. Tool matrix

Table 1a: Platform coverage (of the 9 target networks)

Table 1b: Agent access, hosting, price for one brand

Table 1c: Video, analytics, the catch

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2. The X problem

What changed (all [data] unless noted):

• February 2026: pay-per-use became the default for new X developers; legacy Basic ($200/mo) deprecated after June 1, 2026, Pro ($5,000/mo) deprecated August 14, 2026 with auto-migration after September 1, 2026 [single: https://www.blotato.com/blog/twitter-api-pricing; the X devcommunity announcement at https://devcommunity.x.com/t/x-api-pricing-update-owned-reads-now-0-001-other-changes-effective-april-20-2026/263025 is robots-blocked so I could not read it directly].
• April 2026 (announced April 16, effective April 20): plain post $0.015 per request (was $0.01), post containing a URL $0.20 (was $0.01, a 1,900% increase), owned reads $0.001, third-party reads $0.005, delete $0.01; following, liking and quote-posting removed from self-serve tiers. https://techcrunch.com/2026/04/22/x-makes-it-more-expensive-to-post-links-through-its-api/, https://opentweet.io/blog/x-api-link-post-fee, https://www.blotato.com/blog/twitter-api-pricing. Note TechCrunch quotes $0.105 for a plain post while OpenTweet, Blotato and Zernio all say $0.015; I treat $0.015 as correct and TechCrunch's figure as a typo [opinion].
• Techmeme stripped links from automated posts in response [data: TechCrunch].

Who still posts to X and what it costs you:

Practical implication for a founder posting ~60 X posts a month with a link in a third of them: direct cost is roughly 40 x $0.015 + 20 x $0.20 = $4.60/month [opinion, arithmetic on X's published rates]. The cost is a nuisance, not a blocker; the bigger risk is aggregators dropping X without notice (Hypefury, Later) [opinion].

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3. TikTok and YouTube specifics

TikTok Content Posting API (https://developers.tiktok.com/docs/en/content-posting-api-reference-direct-post) [data]:

• Unaudited clients: "All content posted by unaudited clients will be restricted to private viewing mode." Public posting requires an audit "to verify compliance with our Terms of Service."
• Scope: video.publish; photo posts are a separate endpoint; 6 requests/minute per user token on /v2/post/publish/video/init/.
• Consequence: a self-hosted Postiz/Mixpost or an n8n recipe needs your own TikTok app to pass audit before anything is publicly visible [opinion]. Third-party guides on the audit: https://bundle.social/blog/tiktok-api-approval, https://www.outstand.so/docs/tiktok-audit (not fetched).

YouTube Data API (https://developers.google.com/youtube/v3/determine_quota_cost) [data]:

• Default project quota is 10,000 units/day; the fetched page describes uploads (videos.insert) as a separate bucket allowing up to 100 uploads per day. Older documentation priced videos.insert at 1,600 units (about 6 uploads/day on default quota); the page as fetched today reports the new bucketed model. Either way, a solo founder will not hit it [opinion].
• Unverified OAuth apps: Google requires OAuth app verification for the youtube.upload scope in production; historically unverified apps had uploads locked to private. Not confirmed on this pass [opinion].

Who already holds the approvals (so you skip audit and quota work): every cloud vendor that lists TikTok and YouTube publishing: Buffer, Postiz cloud, Publer, Zernio, Ayrshare, Metricool, SocialBee, Blotato, Socialync, PostFast [data/single per Table 1a]. Self-hosted Postiz, Mixpost and n8n do not; you bring your own apps [opinion, inferred from the TikTok audit rule].

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4. Verdict

Ranked for an agent-run, single-brand account:

1. Postiz cloud, $29/month. Reasons: covers all 9 targets including Reddit and Mastodon [data]; REST API plus webhooks on every plan; hosted MCP endpoint that Claude Code connects to with one URL [data]; ClawHub skill is the most-downloaded social skill (10.1k) [data]; the vendor holds TikTok and YouTube approvals; no X surcharge [data]; open-source escape hatch to self-host later. Catch: 5-channel cap on Standard means you must pick 5 of 9 or pay $39 for Team (10 channels) [data]; MCP docs page is missing; analytics not visible in public API docs.
2. Zernio (formerly Late), about $42/month for 9 accounts plus X pass-through. Reasons: API-first, MCP, webhooks, every feature on every account, video to YouTube and TikTok, transparent X pricing [data]. Catch: no Mastodon, brand-new rename, per-account pricing grows with channels.
3. Buffer, Free to about $54/month. Reasons: official MCP on every plan including Free, GraphQL API, X included with no surcharge, analytics via MCP [data]. Catch: per-channel pricing is the most expensive of the three at 9 channels; Reddit unconfirmed.

Honorable mention: Typefully for X-first writing (best composer, MCP, API) but it cannot reach YouTube, TikTok, Instagram or Reddit, so it is a companion, not the hub [opinion].

Self-hosted option: Postiz on your Kubernetes cluster. Free software, same public API and MCP surface [data: docs.postiz.com/public-api], API rate limit adjustable. Cost is developer-app bureaucracy: you must register X (pay-per-use billing), TikTok (audit before public posts), Google (OAuth verification), Meta (app review for Instagram and Threads), Reddit, LinkedIn apps yourself. Mixpost Pro ($299 one-time) is the alternative if you prefer PHP and a no-subscription license, but it lacks Reddit [data].

Cloud option: Postiz Team at $39/month (10 channels) to fit all 9 networks, or Zernio if Mastodon does not matter.

Recommended starting set of networks [opinion]: X (home), LinkedIn, Bluesky, Threads, Mastodon for text; add YouTube when there is video; skip TikTok and Instagram until there is a video pipeline (both are video/image-first, the brief is text plus occasional cover images); Reddit only for hand-picked subreddits since self-promotional cross-posts get removed. That is 5 channels, which fits Postiz Standard at $29.

Estimated monthly cost [opinion]:

• Cloud path: Postiz Standard $29 (5 channels) or Team $39 (all 9); X posting bundled. Total $29 to $39.
• Self-hosted path: $0 software, roughly $5 to $15 of cluster resources, plus X direct fees of about $5 for 60 posts with 20 links. Total about $10 to $20 plus your time on six developer-app approvals.
• Zernio path: about $42 for 9 accounts plus about $5 X pass-through, about $47.

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5. Counts

• Calls used: 40 of 40 (9 searches, 31 fetches).
• Sources checked: 31 URLs fetched; 5 failed (X devcommunity robots-blocked, docs.postiz.com/public-api/mcp 404, typefully.com/pricing returned no body, fazm.ai 410, docs.mixpost.app/pro/mcp 404).
• Sources used in the brief: 24 distinct URLs.
• Claims by type: roughly 58 [data] from vendor pages or platform docs, 22 [single] from one third-party source (mostly Blotato, socialk.it, topsocialtools, clawskills.sh, PostFast blog, which are competitors and should be read as such), 16 [opinion].
• Notable unverified items: Typefully price ($99/year, Blotato only); Metricool X add-on ($5 vs $10, sources disagree); Postiz MCP on self-hosted (undocumented); Buffer Reddit support; YouTube upload quota model (page summary conflicts with older 1,600-unit figure).