/API TERMS
API Terms/Communication
Category

Communication APIs

75 Communication APIs with verified auth, pricing and rate limits. 60 offer a free tier; 15 document an MCP server. Every field carries the source URL that states it.

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APICategoryAuthPricingFree tierLimitsOpenAPIMCPChecked
AgentMailagentmail.toCommunicationBearer tokenfreemium✓✓✓✓2026-08-03
Telnyx APItelnyx.comCommunicationBearer tokenusage based✓✓✓✓2026-07-12
DropMaildropmail.meCommunicationAPI keyfree✓✓n/d✓2026-07-12
Novu APInovu.coCommunicationAPI keyfreemium✓✓n/d✓2026-07-13
pingutil (EVA)pingutil.comCommunicationBearer tokenfree✓✓✓n/d2026-07-26
PostStackpoststack.devCommunicationBearer tokenfreemium✓n/d✓✓2026-07-08
AutoSendautosend.comCommunicationBearer tokenusage based✓n/dn/d✓2026-08-03
ImprovMXimprovmx.comCommunicationBasic authfreemium✓✓n/dn/d2026-07-26
Kiprio Email Validatekiprio.comCommunicationAPI keyfreemium✓✓n/dn/d2026-07-08
LiveKit APIlivekit.ioCommunicationAPI keyfreemium✓✓n/d✓2026-07-26
UserCheck (formerly MailCheck.ai)mailcheck.aiCommunicationBearer tokenfreemium✓✓n/dn/d2026-07-08
Bird APImessagebird.comCommunicationAPI keyfreemium✓✓n/d✓2026-07-13
Resend APIresend.comCommunicationAPI keyfreemium✓n/d✓✓2026-07-13
The SMS Works APIthesmsworks.co.ukCommunicationBearer tokenusage based✓✓n/dn/d2026-07-12
Twilio REST APItwilio.comCommunicationBasic authusage based✓n/d✓n/d2026-07-12
Zoom APIzoom.usCommunicationOAuth 2.0freemium✓✓n/dn/d2026-07-12
Courier APIcourier.comCommunicationAPI keyusage based✓n/dn/d✓2026-07-26
D7SMSd7networks.comCommunicationBearer tokenusage based✓n/dn/dn/d2026-07-12
Knock APIknock.appCommunicationAPI keyfreemium✓n/dn/d✓2026-07-13
Loops APIloops.soCommunicationn/dfreemium✓n/dn/d✓2026-07-13
Mail.tmmail.tmCommunicationBearer tokenfree✓✓n/dn/d2026-07-08
mailboxlayermailboxlayer.comCommunicationAPI keyfreemium✓n/dn/dn/d2026-07-08
Mailchimpmailchimp.comCommunicationAPI keyfreemium✓✓n/dn/d2026-07-08
Plivo APIplivo.comCommunicationBasic authusage based✓n/dn/dn/d2026-07-13
Postmark Account-level APIpostmarkapp.comCommunicationAPI keyfreemium✓n/dn/dn/d2026-07-08
Brevo (formerly Sendinblue)sendinblue.comCommunicationAPI keyfreemium✓✓n/dn/d2026-07-12
sms77.io API (now seven.io)sms77.ioCommunicationAPI keyusage based✓n/dn/d✓2026-07-26
WhatsHubwhatshub.devCommunicationAPI keyfreemium✓n/dn/dn/d2026-08-17
Zoom Connectzoomconnect.comCommunicationAPI keyusage basedn/d✓n/dn/d2026-07-12
BulkSMS JSON REST APIbulksms.comCommunicationn/dusage based✓n/d✓n/d2026-07-08
ClickSend REST API v3clicksend.comCommunicationBasic authusage based✓n/dn/dn/d2026-07-12
Cloud-RF APIcloudrf.comCommunicationAPI keyfreemium✓n/dn/dn/d2026-07-26
EmailJSemailjs.comCommunicationn/dfreemium✓✓n/dn/d2026-07-26
Front APIfront.comCommunicationn/dpaid✓✓n/dn/d2026-07-26
Gorgias APIgorgias.comCommunicationn/dpaid✓✓n/dn/d2026-07-26
Help Scout APIhelpscout.comCommunicationn/dfreemium✓✓n/dn/d2026-07-26
Kickboxkickbox.comCommunicationAPI keyusage based✓n/dn/dn/d2026-07-26
Kustomer APIkustomer.comCommunicationn/dcontact salesn/d✓n/d✓2026-07-16
Mailgun APImailgun.comCommunicationAPI keyfreemium✓n/dn/dn/d2026-07-13
OneSignalonesignal.comCommunicationn/dfreemium✓n/dn/d✓2026-07-26
SIGNL4 APIsignl4.comCommunicationAPI keyfreemium✓n/dn/dn/d2026-07-26
The SureVoIP RESTful APIsurevoip.co.ukCommunicationOAuth 2.0free✓n/dn/dn/d2026-07-26
Agora APIagora.ioCommunicationotherfreemium✓n/dn/dn/d2026-07-13
Aircall APIaircall.ioCommunicationn/dcontact sales✓n/dn/dn/d2026-07-26
Airtelairtel.lvCommunicationn/dusage based✓n/dn/dn/d2026-07-12
CallFire APIcallfire.comCommunicationn/dfreemium✓n/dn/dn/d2026-07-26
Daily APIdaily.coCommunicationn/dfreemium✓n/dn/dn/d2026-07-26
Freshdesk APIfreshdesk.comCommunicationn/dfreemium✓n/dn/dn/d2026-07-26
Guerrilla Mailguerrillamail.comCommunicationn/dfreemium✓n/dn/dn/d2026-07-26
Intercom APIintercom.comCommunicationn/dfreemium✓n/dn/dn/d2026-07-26
MailboxValidator Free Email Checkermailboxvalidator.comCommunicationn/dfreemium✓n/d✓n/d2026-07-26
Mandrill (Mailchimp Transactional)mandrillapp.comCommunicationn/dpaid✓n/dn/dn/d2026-07-26
RingCentral APIringcentral.comCommunicationn/dcontact sales✓n/dn/dn/d2026-07-26
Sakarisakari.ioCommunicationn/dfreemium✓n/dn/dn/d2026-07-12
Sendbird APIsendbird.comCommunicationn/dfreemium✓n/dn/dn/d2026-07-13
SendGrid Email Activity API (beta)sendgrid.comCommunicationAPI keyfreemium✓n/dn/dn/d2026-07-26
Sinchsinch.comCommunicationn/dusage based✓n/dn/dn/d2026-08-03
Webex APIwebex.comCommunicationn/dfreemium✓n/dn/dn/d2026-07-26
WINSMSwinsms.co.zaCommunicationn/dusage based✓n/dn/dn/d2026-07-26
Zendesk APIzendesk.comCommunicationn/dpaid✓n/dn/dn/d2026-07-26
WhatsApp Business Platform APIbusiness.whatsapp.comCommunicationn/dusage based✓n/dn/dn/d2026-07-16
Dialpad APIdialpad.comCommunicationn/dcontact salesn/dn/dn/dn/d2026-07-26
iSendPro APIisendpro.comCommunicationn/dpaid✓n/dn/dn/d2026-07-12
Reloadly Airtime Top-ups APIreloadly.comCommunicationn/dusage basedn/dn/dn/dn/d2026-07-12
Account APIvonage.comCommunicationn/dusage basedn/dn/dn/dn/d2026-07-26
Cherttrychert.comCommunicationn/dcontact salesn/dn/dn/dn/d2026-07-27
Call Control APIcallcontrol.comCommunicationn/dn/dn/dn/dn/dn/d2026-07-26
mail.gwmail.gwCommunicationn/dn/dn/dn/dn/dn/d2026-07-26
Verifiermeetchopra.comCommunicationn/dn/dn/dn/dn/dn/d2026-07-26
Neutrino APIneutrinoapi.netCommunicationn/dn/dn/dn/dn/dn/d2026-07-12
Account APInexmo.comCommunicationn/dn/dn/dn/dn/dn/d2026-07-26
NotifyGatenotifygate.comCommunicationn/dn/dn/dn/dn/dn/d2026-07-27
Mobility APIo2.czCommunicationn/dn/dn/dn/dn/dn/d2026-07-26
Smartphone Test Farm (STF)openstf.ioCommunicationn/dn/dn/dn/dn/dn/d2026-07-12
Telegram Bot APItelegram.orgCommunicationn/dn/dn/dn/dn/dn/d2026-07-12