Zernio Review 2026: Social media API and MCP server for posting, DMs, analytics and ads from code, priced per connected account with the first 2 free

The full review

What Zernio is

Zernio is a single API that a developer, a SaaS product or an AI agent calls to publish to social networks, answer comments and DMs, read analytics and run ads. Its homepage headline is “Marketing infrastructure for agents”, the page says “One integration covers social, blogs, messaging, voice, and ads.”, and its first code sample calls POST /v1/posts. The pricing page says Zernio is “built for developers and teams with technical resources”, and names n8n, Make and Zapier as the route for people who do not write code.

Zernio is the new name of Late. Its rebrand page says “Late is now Zernio.”, getlate.dev redirects to zernio.com, and API keys, endpoints and webhooks carry over unchanged. The Impressum names the company as ZERNIO SOFTWARE SL of Palamós, Girona, Spain, and the About page lists it as founded in 2025, based in Girona, bootstrapped and 9 people strong, with Miki Palet as founder.

The homepage asks readers to “Join 200,000+ of the world’s most ambitious developers and builders” and describes the product as “One integration for every channel. Official APIs only”. Both are the vendor’s claims, not figures we could check, as is its FAQ line that custom integrations take 8 to 12 months while Zernio “takes under an hour”. The FAQ also says Zernio is white-label friendly: “Your users never see Zernio branding.” Its docs page on using your own platform apps does not match that line: accounts connected without your own app “keep running on Zernio’s app”. For the consent screen to show your app’s name and logo, you add your own app on each platform, and on Instagram and Facebook that app needs the platform’s App Review with advanced access before outside accounts can connect. The same page says ads connections and WhatsApp’s Embedded Signup stay on Zernio’s app even then.

What the API covers

The docs’ platforms page says you can “publish to 16 of them with one request shape”. It lists 12 social networks for posting: X, Instagram, Facebook, LinkedIn, TikTok, YouTube, Pinterest, Reddit, Bluesky, Threads, Google Business Profile and Snapchat. Snapchat cannot be used yet: the platforms page and the support table badge it “Closed beta”, but its own docs page says “Snapchat is not available yet: Snap has not approved Zernio’s app”, so new connections return 403 for every account, with no access list to join and no release date, while Zernio’s marketing page for Snapchat promises “No allowlist needed - start posting immediately”. Reddit has no badge on the platforms page, and the support table ticks it for posts, DMs, comments and analytics, but its own docs page opens with “Reddit is temporarily unavailable”: Reddit has blocked third-party apps, posts fail, messages and analytics stop syncing, and Reddit-only endpoints return 503. Reddit Ads is not affected. The changelog dates this to October 20, 2026, and zernio.com/reddit shows the same warning. WhatsApp, Telegram, Discord and Slack also take posts; with the 12 social networks that makes the 16 the docs quote. The docs’ support table also ticks Post for the four blog platforms (blog articles only) and for HubSpot and Google Analytics, whose format column reads None. Beyond posting, the docs list messaging on WhatsApp, RCS, iMessage, Telegram, Discord and Slack; phone numbers, voice calls and SMS; 9 ad networks (Meta, Google, LinkedIn, TikTok, Pinterest, X, OpenAI, Reddit and Microsoft Ads); blog articles on Shopify, WordPress, Wix and Webflow; HubSpot, which syncs inbox contacts and messages; Google Analytics; and Google and Microsoft accounts for email, calendar, files and contacts, which the homepage banner announces as new.

What you can do differs by network, and the per-platform pages qualify the support table’s ticks. The table marks posts, analytics, DMs and comments for X, Instagram, TikTok, Reddit and Bluesky, and Facebook adds reviews; on TikTok, DMs are replies only, on Business Accounts registered outside the EEA, Switzerland and the UK, and comments need a connection through TikTok’s Business app, while Reddit and Bluesky DMs are text only (and Reddit is unavailable for now, as above). LinkedIn, YouTube and Threads have posts, analytics and comments but no DMs; LinkedIn comments are for organization pages only, and its page says “LinkedIn blocks third-party DM access”. Pinterest and Snapchat are marked for posts and analytics only, and Google Business Profile for posts, analytics and reviews, with its analytics at location level only. iMessage and SMS are DMs only. Discord is ticked for posting only; its page adds that the bot sends DMs, outbound only, with no DM inbox. Telegram’s inbox covers the connected group or channel only, and private DMs to the bot are not stored. The TikTok, Reddit and Bluesky pages call their analytics limited. The pricing FAQ says video can be scheduled to YouTube, TikTok, Instagram (Reels), Facebook, LinkedIn and Pinterest.

The vendor’s own counts do not agree, so we report them as they stand. The homepage says “Sixteen networks, one API.” while its footer lists 12 social networks. Its FAQ names 16 channels, a list that leaves out Reddit and includes iMessage, which the docs mark for DMs only. The affiliate page says 15 platforms, the API reference overview says the API spans 30, and the docs’ platforms index lists 38 across its 8 categories.

Pricing: per connected account, with 2 free

There are no plans to pick and no seats. The pricing page says “Every feature included, no plans, no seats.” Its self-serve option, Build, is “Usage-based, card on file.”, and Enterprise is custom-priced and “Available past 2,000 accounts”. You pay per connected account per month on a graduated ladder: the first 2 accounts are free, accounts 3 to 10 cost $6 each, 11 to 100 cost $3 each and every account from 101 costs $1, with no cap. The same page’s FAQ words the first band differently: “The first 2 accounts are free. After that, pricing is graduated: $6/account for 1-10”; the slider and the pricing docs say 3 to 10. Since the billing docs grant the 2 free accounts as a $12 monthly credit, both wordings give the same bill (10 accounts come to $48 either way, by our arithmetic), but the pages still disagree on the wording. Each band prices only the accounts inside it. The page offers no annual billing and mentions no discount, and neither card is labelled popular or recommended. The Enterprise page adds that most enterprise contracts include volume-based discounts on the public ladder.

A connected account is any active connection: a posting account such as an Instagram account, a Facebook Page or a YouTube channel, an ad account, a WhatsApp number (which also pays its number fee), an iMessage sender (on top of its $200 a month, per the iMessage docs), a creator account tracked in a creator campaign (per the pricing page) or a connected blog site or store. SMS and voice on a number never count. Profiles, which group the accounts of one brand or customer, are free. The docs give the example that “A Page, its Instagram account and the Meta ad account behind them are 3.”

Billing is prorated by the day. The docs add up the month’s account-days, divide them by 30 and run that total through the ladder, so an account connected for half the month counts as half an account. The free tier appears in the billing docs as a flat $12 credit each calendar month, “which covers the first 2 accounts at the $6 rate”. A card is needed before the third account or the first X account, and payment is by Visa, MasterCard or American Express through Stripe.

Two pages disagree on when you pay. The pricing FAQ says you pay per account per month, “billed at the end of each billing period”; the billing docs say “Zernio charges your card as you accrue usage, not once at the end of the month”, starting at a $10 threshold that then doubles. There is no prepaid time to refund: you stop charges by disconnecting accounts, and the FAQ says billing errors and charges caused by an outage on Zernio’s side are credited. Support is chat and email on Build and a dedicated Slack channel on Enterprise, where postpaid invoicing on net-30 or net-60 terms is available.

The pricing page says “Every feature included, nothing gated behind a plan”, and its FAQ says “No add-ons, no feature tiers.” The API reference treats many of its add-on notes as legacy: “Legacy plans need the Analytics add-on; included by default on usage-based plans”, and the same for Ads. But its ads sections (Ad Campaigns, Ad Insights and Ad Rules among them) still say “Requires the Ads add-on.”, a few analytics endpoints say “Requires the Analytics add-on.” and several inbox endpoints say “Requires Inbox addon”, all without that qualifier, so the pages still disagree and we report both.

What a small product pays

Worked examples from the published ladder, per month, before X API calls, other metered extras and any tax: 2 accounts cost $0. One brand with a Facebook Page, its Instagram account and its Meta ad account is 3 accounts and costs $6. 5 accounts cost $18 (3 × $6), and 10 accounts cost $48 (8 × $6), the $4.80 average the pricing page shows. The docs’ 12-account example comes to $54. 25 accounts cost $93 ($48 for accounts 3 to 10 plus 15 × $3), and 100 accounts cost $318 ($48 plus 90 × $3). With no annual price, 10 accounts held all year cost $576.

X adds its own charges per API call, passed through at X’s published rates with no markup: $0.015 to create a post, $0.200 for a post with a link, $0.005 per post read for analytics or lookups, $0.010 per DM read and $0.015 per DM sent. The docs bill reads and DMs per resource, while the pricing page shows every X rate per request; the pricing page also lists user reads, follows and X Article actions at $0.010 per request, so an X Article costs $0.020. There is no X spend cap until you set one in the dashboard, and at 100% of it posts are refused and analytics and inbox sync pause. Thirty X posts with links in a month add $6.00, the price of one more account in the $6 band; thirty without links add $0.45.

Two other meters apply to everyone who uses them. Messages you send from the inbox are free up to 10,000 a month, then $1 per 10,000; received messages, comments and reviews never count. Managed ads are free for the first 500 active ads, then $0.01 per active ad per month, and the vendor says it never takes a percentage of ad spend.

Against the other social media APIs we price on the same monthly basis, 10 accounts (an Instagram and a LinkedIn account for each of 5 brands) cost $19 at Outstand (3,000 posts included), $24 at Upload-Post, $29 at Blotato and $39 at Postiz, then $48 at Zernio, $55.00 at Unipile, $63.00 at Publer and $299 at Ayrshare, which puts Zernio fifth of eight in our ranking. Each vendor prices on its own unit (accounts, channels, profiles or posts), and what each plan leaves out is set out in that ranking and in each review. Buffer, a scheduling dashboard with an API, charged $60 a month for 10 channels on Essentials billed monthly ($6 per channel, $5 billed yearly) on its pricing page on November 6, 2026.

Messaging, phone numbers and other extras

The communication side is priced per item, on Zernio’s invoice apart from WhatsApp’s Meta fees (below). Dedicated phone numbers are sold in 55 countries, plus 12 more by pre-order, at a flat monthly price per number that the docs put between $3 and $30, charged in full at activation and again on the 1st of each month. The pricing page lists calls, inbound and outbound, from $0.01 a minute depending on the destination; the phone pricing docs give that rate for outbound calls and say inbound minutes have no rate card and bill at the carrier’s settled cost. Recording costs $0.004 a minute, and US-only branded calling is $100 a month per brand plus $0.10 per branded outbound call. Outbound SMS starts at $0.008 per segment. On inbound SMS the pages differ: the pricing page lists $0.010 per received segment on US numbers, while the phone pricing docs say inbound SMS is free on most numbers and bills at the per-segment rate only where the carrier charges an inbound fee, on some US routes. Texting in the US also needs a one-time $9 10DLC registration and a campaign fee of $20 a month ($4 for sole proprietors, per the docs).

WhatsApp has two billers, the docs say. Meta bills template messages, service messages beyond 1,000 per number a month and outbound call minutes, and those fees “appear on your Meta invoice”, charged to the payment method on your WhatsApp Business Account; the pricing page says service messages were free until 30 September 2026 and that from 1 October 2026 Meta charges for them after 1,000 free per number each month. Zernio bills the number, the carrier leg of calls and outbound WhatsApp messages, which count toward its inbox meter, and each WhatsApp number is also a connected account. An iMessage sender costs $200 a month plus the connected-account fee, the iMessage docs say, with messages at $0, and it is non-refundable once activated. The pages disagree on how fast a sender can reach new contacts: the pricing page allows 1,000 new conversations per sender a day, while the iMessage docs allow one every 15 minutes, starting at 2 a day and rising to 50 over three weeks. An RCS agent needs a $150 setup and, in the US, a $750 one-time carrier approval (usually 4 to 6 weeks, the pricing page says); the docs then charge $160 a month per agent in the US and $75 elsewhere, which the pricing page shows as “from $75/mo”, and US messages start at $0.0098 each. The same pricing page’s FAQ says there are no setup fees. Creator payout transfers carry a fee of 4%, $0.50 minimum, added on top of the transfer. Funding that balance by card adds Stripe’s card fee on top, 3.15% + 30¢ on a US card, the pricing page says, and the money can be paid out to creators 7 days after the charge.

SDKs, MCP and agent tools

The REST API lives at https://zernio.com/api/v1 and takes an API key as a Bearer token. Its endpoint groups cover profiles, connecting accounts, accounts, posts, media, messages, comments, analytics, campaigns and ads, and webhooks. The Create post reference shows a rate limit of 25 posts per hour per account and support for an Idempotency-Key, and the Posts group also covers bulk upload from CSV, retrying a failed post, editing a published post, pinning and post approval. Zernio ships official SDKs for 8 languages, Node.js, Python, Go, Ruby, Java, PHP, .NET and Rust, all generated from one OpenAPI 3.1 spec.

For AI assistants there is a hosted MCP server at https://mcp.zernio.com/mcp. The docs say it works with Claude, Claude Code, ChatGPT, Codex, Cursor, Windsurf, VS Code and any other MCP client, that people sign in with their Zernio account, and that autonomous agents send an API key instead. The homepage lists Claude Code, Cursor, Codex, Grok bot, OpenAI dots, Meta Muse, OpenClaw and Hermes under Works with, and there is also a CLI (@zernio/cli) and a Chat SDK adapter. The vendor’s MCP tool counts disagree: the homepage FAQ says 496 tools, the affiliate page says 280+, and the docs describe 20 core tools plus one generated tool per API endpoint. An unauthenticated tools/list request we sent on November 6, 2026 returned HTTP 401, although the docs say that call needs no credential.

Webhooks are signed: the X-Zernio-Signature header carries an HMAC-SHA256 of the raw request body, keyed by a secret you set. You can create up to 50 webhook endpoints per user, and an event goes to a dead-letter queue after its 7th failed delivery. The docs publish an llms.txt file and the OpenAPI spec, the Create post page has a Copy for AI button, and the public changelog held more than 1,000 entries on November 6, 2026, the newest dated that day. The versioning policy says “A breaking change ships only as a new path version.”

Limits and reliability

Request limits are counted across the whole team and rise with connected accounts: 60 requests a minute with 0 to 2 accounts (6 a second on analytics endpoints), 600 with 3 to 2,000 (10 a second) and 1,200 above 2,000 (20 a second). Each account can publish at most 25 posts an hour, with daily caps of 100 on Instagram and Facebook, 250 on Threads, 50 on X, 25 on Pinterest, 15 videos and 15 photos on TikTok Business app connections, and 50 on every other platform. The “unlimited posts” on the pricing page are, in the docs’ words, “subject to the per-account rate limits”. Post analytics are cached for 60 minutes, and follower counts refresh once a day.

Zernio retries a platform’s 429 or 5xx response up to 3 times. Its rate-limits guide also says platforms add their own limits, “some shared by every customer because Zernio is one application”, and the guide names Reddit’s request budget, Google Ads’ single developer token and TikTok’s direct-posting cap on developer-app connections among them (Reddit itself is unavailable for now; see What the API covers). On X, DMs are limited to 200 requests per 15 minutes and 1,000 per 24 hours per connected account, and the docs say customers who bring their own X API key need X’s Pro tier, which the docs price at $5,000 a month, or Enterprise access to send DMs.

Uptime figures differ by page: the homepage footer says 99.97%, the pricing FAQ and the affiliate page say 99.7%+, and the status page showed 99.990% for the dashboard and the public API over 90 days. On November 6, 2026 the status page read “All services are online” and its Previous incidents section listed two resolved incidents. From about 19:00 to 22:30 UTC on November 4, some customers saw timeouts when connecting to the MCP server from AI tools. The incident notes say the API and dashboard were not affected, though the incident page lists Public API as the affected service. From about 02:00 UTC on November 3 to about 04:40 UTC on November 4, many attempts to connect a TikTok account failed at the authorization step. The same page’s 90-day history lists more. Besides that MCP incident, five name the dashboard or the public API as affected: on August 21, from 14:01 to 14:59 UTC, what the vendor calls a “minimal and transient spike from our database system”, with “No data loss” (Dashboard and Public API); on September 28, from 14:18 to 15:10 UTC, “delays in outbound webhook delivery due to elevated event volume” (Dashboard); on October 8, “Between 14:44 and 15:52 UTC, some customers saw the dashboard and API respond slowly or time out”; on October 19, “Between 19:10 and 19:31 UTC, new posts could not be created from the dashboard or the API”; and on October 26, “Between 21:18 and 21:37 UTC, many API requests failed and some accounts could not load in the dashboard.” It also logs incidents on other parts of the service: new comments not detected for some accounts from October 8 until a fix on October 12, though the incident was opened only on October 12 and the daily bars log 7 hours and 54 minutes of degradation; WhatsApp sends failing for some accounts on October 15; incoming events and WhatsApp messages arriving late on October 23, 26 and 28 (on October 23, between 13:35 and 14:05 UTC, some accounts also saw dashboard logins fail); and Reddit posting and account connections failing from 15:34 UTC on October 19 until the incident was closed at 02:32 UTC on October 21 (the daily bars log downtime on all three days), with the closing update saying “Reddit is temporarily unavailable” because Reddit has blocked third-party apps from its API. Four more are publishing incidents: some Google Business Profile posts with images failed to publish from September 27 to September 30; some Instagram posts scheduled before their account was reconnected with a different login type could fail to publish from October 4 until 09:08 UTC on October 5; and on October 19 some TikTok posts failed between 02:24 and 03:28 UTC, when requests to TikTok failed intermittently, and some Pinterest video pins could fail to publish between 16:55 and 20:30 UTC. Zernio puts the comment incident, the October 23 and 28 delays and the Google Business Profile and Instagram failures down to an issue on its side.

Security, compliance and data location

Zernio’s trust portal, run on Comp AI, lists SOC 2 Type 2 and GDPR as compliant, and the SOC 2 Type II report is available on request with a work email; we have not seen it. The Enterprise page says SAML and OIDC single sign-on is self-serve on every workspace and SCIM is enabled on enterprise contracts, with owner, admin, member, viewer and billing roles. The pricing page’s Enterprise card lists SAML SSO, SCIM, MFA, audit logs and RBAC.

The vendor states where data lives in two ways. The Enterprise FAQ says “your data is stored and processed within Europe”, while the trust portal lists the Axiom logging and monitoring datasets on Axiom’s US East (Northern Virginia) deployment. If EU-only processing matters to you, ask before you sign.

Who Zernio fits, and who should look elsewhere

Zernio fits developers building a product that posts, replies or reports on social networks for its users, agencies and platforms that run many accounts, and people connecting an AI agent to social channels through MCP. The free tier is enough for a 2-account prototype with the full API, and the price per account drops from $6 to $3 after 10 accounts and to $1 after 100.

It is the wrong buy if your team wants a social media scheduler it can use without writing code: the vendor says it is built for developers and teams with technical resources, and the scheduling apps in our Social Media Management niche, such as Buffer, are made for that job. Heavy X publishers should budget for X’s per-call charges, Reddit and Snapchat are listed, but their docs pages say Reddit is temporarily unavailable and Snapchat is not available yet, LinkedIn has no DMs (its page says LinkedIn blocks third-party DM access), and teams that need EU-only processing should ask about the US logging region first.

The catches

On Trustpilot, Zernio scored 4.8 (Excellent) from 213 reviews when we read the page on November 6, 2026. Trustpilot itself notes that “This company hasn’t invited customers recently, so reviews may not be representative”, and the profile was claimed in April 2026. G2’s page blocked our requests, so we show no G2 score. The homepage’s structured data declares a 4.8 rating from 50 ratings of its own; that is the vendor’s markup, not a third-party score, and we do not use it.

The vendor’s pages disagree on several basic facts: the number of platforms (16, 15, 30 or 38), the number of MCP tools (496, 280+, or 20 core tools plus generated ones), uptime (99.97%, 99.7%+ or 99.990%), whether Reddit is available (listed without a warning on the platforms page and support table, “temporarily unavailable” on its docs page), whether Snapchat is available (badged closed beta in the docs, “not available yet” on its docs page, “start posting immediately” on its marketing page), how many new contacts an iMessage sender may message a day (1,000 on the pricing page; 2 at first, rising to 50, in the docs), when the card is charged, whether add-ons exist (the pricing FAQ says “No add-ons”; the API reference calls many of its Analytics and Ads add-on notes legacy, but its ads sections and several analytics and inbox endpoints still require an add-on with no such qualifier), whether there are setup fees (none, says the pricing FAQ; $150 per RCS agent, says the same page’s rate card), whether X reads are billed per request or per resource, how inbound calls and US inbound SMS are charged, which accounts the $6 band covers (1-10 in the pricing FAQ, 3 to 10 in the docs), whether users ever see Zernio branding (never, says the homepage FAQ; accounts connected without your own app “keep running on Zernio’s app”, say the docs), and where data is processed. Its comparison page also labels Buffer “No public API”, while Buffer’s own pricing page listed API access on every plan, including 1 API key on Free with 1,000 requests per connected channel, up to 3,000, over a 30-day window in its comparison table (“per channel/month” on its plan cards), when we read it on November 6, 2026. Confirm any number you build on in the docs and on your own usage page, where the vendor says every call, message and number is an itemized line.

Key features

How Zernio compares

Head-to-head: Zernio vs Outstand · Zernio vs Upload-Post · Zernio vs Blotato · Zernio vs Postiz · Zernio vs Unipile · Zernio vs Publer · Zernio vs Ayrshare

Frequently asked questions