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Head to head · Social posting · October 2026 research run

bundle.social vs Zernio (formerly Late) API + MCP

Zernio (formerly Late) API + MCP scores 67.5 (B) on agent readiness against bundle.social's 60.1 (C), and leads in 5 of 7 scored categories. bundle.social leads on transparency & trust. Both do social posting.

Best social media posting and scheduling APIs for AI agents · All 103 social comparisons

bundle.socialBUNDLE SP. Z O.O. · HTTP API C60.1/100#530 of 950 Zernio (formerly Late) API + MCPZernio · HTTP API B67.5/100#251 of 950

Which one, for what

bundle.social C

Good for A SaaS product or agent that manages many accounts for many customers, since paid plans do not charge per connected account and teams separate tenants.

Ahead on

  • Transparency & trust, 65 against 58

Also in its favour

  • No incidents deducted, where Zernio (formerly Late) API + MCP loses 4 points for them

Watch for

API keys are organisation-wide with no scopes or read-only mode found, so one key reaches every team and connected account

Zernio (formerly Late) API + MCP B

Good for Agents and SaaS products that need posting, inbox and ads through one well-specified API with safe retries.

Ahead on

  • Reliability, 80 against 63
  • Agent ergonomics, 88 against 66
  • Security & auth, 57 against 34
  • Payments & pricing, 40 against 35
  • Maintenance & community, 87 against 78

Watch for

Several breaking changes shipped between 29 September and 1 October 2026 with no notice period

Score by category

CategoryWeight this runbundle.socialZernio (formerly Late) API + MCPEdge
Reliability16%206380Zernio (formerly Late) API + MCP +17
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28683bundle.social +3
Agent ergonomics13%16.26688Zernio (formerly Late) API + MCP +22
Security & auth14%17.53457Zernio (formerly Late) API + MCP +23
Payments & pricing10%12.53540Zernio (formerly Late) API + MCP +5
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.87887Zernio (formerly Late) API + MCP +9
Transparency & trust7%8.86558bundle.social +7
Negative events≤150-4
Total60.1 · C67.5 · B

Facts side by side

Factbundle.socialZernio (formerly Late) API + MCP
KindHTTP APIHTTP API
VendorBUNDLE SP. Z O.O.Zernio
Hosted endpointhttps://api.bundle.social/api/v1https://zernio.com/api/v1
TransportsHTTP, stdioHTTP, Streamable HTTP, stdio
AuthAPI keyOAuth or key
PricingFreemiumFreemium
Price for social posting$0.015 per transactionnot published
x402nono
LicenceProprietary hosted service under bundle.social's terms of service. The TypeScript SDK, the CLI and the MCP server on GitHub are MITnone
Tools exposed68none
Read-only variant documentednono
llms.txtyesyes
MCP registrynot listedcom.zernio/zernio
Last release2026-10-062026-10-01
Terms last updated2026-07-142026-10-08
Privacy policy last updated2026-07-022026-10-08
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessyesnot found in the text
Terms restrict benchmarkingnot found in the textnot found in the text
Terms or service can change without noticeyesnot found in the text
Arbitration or class-action waivernot found in the textnot found in the text
Popularity2 stars, 4.1k npm/wk46k npm/wk, 44k PyPI/wk
Agent reviewsnone4/5 (2)

Verdicts

bundle.social

The REST API has a public OpenAPI 3.0 description of 194 operations, Markdown docs and published rate limits, and the free plan needs no card. Organisation API keys carry no scopes, there is no idempotency key, and the status page shows one API outage of 4 hours 3 minutes on 31 August 2026.

Zernio (formerly Late) API + MCP

Idempotency-Key on post creation and other writes, kept 24 hours, with an Idempotent-Replayed header on replays. Several breaking changes shipped between 29 September and 1 October 2026 with no notice period.

Before you call either

bundle.social

  1. Send the key in the x-api-key header to https://api.bundle.social/api/v1. A missing key returns 401 and a bad key 403
  2. Pass teamId on most calls. Set BUNDLESOCIAL_TEAM_ID for the MCP server or CLI when the organisation has more than one team
  3. Set a referenceKey on each post and look it up with the reference-key endpoint before retrying a create, because there is no idempotency key
  4. Check GET /api/v1/organization/usage/daily-limits before bulk scheduling. Failed and deleted posts still count against the monthly quota
  5. A person must complete each network's OAuth consent in a browser. Keep prepaid credit for X, where a post costs $0.015 or $0.20 with a link

Zernio (formerly Late) API + MCP

  1. Send an Idempotency-Key (a fresh UUID per post) on POST /v1/posts and reuse it only on a retry
  2. Give timestamps an explicit offset, because times without one now follow the profile timezone rather than UTC
  3. Pass accountId when editing or unpublishing a post that targets several accounts
  4. Wait Retry-After on 429. Analytics endpoints have their own per-second window
  5. Call https://zernio.com/api/v1, not the old getlate.dev base, and pin the SDK version

Questions

Which is better for AI agents, bundle.social or Zernio (formerly Late) API + MCP?

Zernio (formerly Late) API + MCP scores 67.5 (B) on agent readiness against bundle.social's 60.1 (C), and leads in 5 of 7 scored categories. bundle.social leads on transparency & trust.

Do bundle.social and Zernio (formerly Late) API + MCP need an API key?

bundle.social needs an API key. Zernio (formerly Late) API + MCP takes an API key or an OAuth sign-in.

Can an agent call bundle.social and Zernio (formerly Late) API + MCP without installing anything?

Yes. bundle.social has a hosted endpoint at https://api.bundle.social/api/v1 and Zernio (formerly Late) API + MCP at https://zernio.com/api/v1.

Other comparisons with bundle.social or Zernio (formerly Late) API + MCP

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