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Warmerly Smartlead
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API

One row, in depth: what each tool does, the verified numbers, and who each suits.

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Smartlead details read from its pricing page, home page and help centre on 17 and 19 October 2026.

Warmerly

Agency plan

Smartlead

Listed as a plan feature; which plans include it is not readable on the pricing page

The short answer

API, in one look.

Both have a public REST API and both put it above the entry plan. Warmerly's API keys, API and webhooks are Agency only ($179 a month, also in the 7-day Agency trial), while its MCP server is on every plan. Smartlead's text pricing page shows API and webhooks on Pro ($94 a month) and above, not on Base ($39), though its rendered pricing page does not show this clearly. Smartlead publishes its rate limits (60 a minute and 1,000 an hour on its Standard tier, 120 a minute and 3,000 an hour on its Pro tier) and has more documented endpoints and webhook events. Warmerly's default is 60 a minute per key, up to 120. Last checked 19 October 2026.

Warmerly

Agency plan

Smartlead

Listed as a plan feature; which plans include it is not readable on the pricing page

The picture

Drawn side by side.

What each price unlocks

Plan prices to scale, a month, with what the API route needs

WarmerlySmartlead
WarmerlyThe API starts at $179. The MCP server is on every plan.
  1. Free$0MCP
  2. Starter$19MCP
  3. Growth$49MCP
  4. Agency$179MCPAPIWebhooks
SmartleadThe API starts at $94 on its text pricing page. Base has none.
  1. Base$39No API or webhooks
  2. Pro$94APIWebhooksCRM access
  3. Unlimited Smart$174APIWebhooksCRM access
  4. Unlimited Prime$379APIWebhooksCRM access
Monthly plan prices and what each unlocks for the API route
CompanyPlanMonthly priceAPI route
WarmerlyFree$0MCP
WarmerlyStarter$19MCP
WarmerlyGrowth$49MCP
WarmerlyAgency$179MCP, API, Webhooks
SmartleadBase$39No API or webhooks
SmartleadPro$94API, Webhooks, CRM access
SmartleadUnlimited Smart$174API, Webhooks, CRM access
SmartleadUnlimited Prime$379API, Webhooks, CRM access

Bars are the monthly list prices. Warmerly's MCP server is on every plan and signs in with OAuth. Smartlead's pricing text says Base does not include API and webhooks, and gives the date it was accurate as of: 28 July 2026. Its rendered pricing page did not make the plan rows readable.

Calls you can make in an hour

The most requests one key can send, from each company's published limit

WarmerlySmartlead
  1. Warmerly, default key60 a minute3,60060 a minute, worked out
  2. Warmerly, key set to 120120 a minute7,200120 a minute, worked out
  3. Smartlead, Standard tier60 a minute1,0001,000 an hour, published
  4. Smartlead, Pro tier120 a minute3,0003,000 an hour, published
Most requests one API key can send in an hour
LimitPer minuteMost in an hour
Warmerly, default key603,600
Warmerly, key set to 1201207,200
Smartlead, Standard tier601,000
Smartlead, Pro tier1203,000

Warmerly's 3,600 and 7,200 are 60 and 120 a minute for 60 minutes. We found no separate hourly cap, so the real ceiling may be lower. Smartlead publishes 1,000 an hour for its Standard tier and 3,000 for its Pro tier, plus a burst of 10 a second and 20 a second, and does not say which plan sits in which tier. Its Enterprise limit is custom. Three heavy endpoints have their own limit of 10 requests per 60 seconds.

When a webhook fails

Retry timing on a log scale, from 0.1 seconds to 6 hours

WarmerlySmartlead
Warmerly
1start20.5 s31.5 s

3 attempts, 0.5 seconds then 1 second apart, over about 1.5 seconds. A failed event is not redelivered later, and 10 failed sweeps in a row switch the subscription off.

Smartlead
0start11 min25 min315 min41 hour56 hours

Retries after 1 minute, 5 minutes, 15 minutes, 1 hour and 6 hours, and the webhook is disabled after 5 failed attempts.

Webhook delivery retries
CompanyAttemptTiming
Warmerly1First delivery
Warmerly20.5 seconds later
Warmerly31 second after attempt 2
SmartleadRetry 11 minute
SmartleadRetry 25 minutes
SmartleadRetry 315 minutes
SmartleadRetry 41 hour
SmartleadRetry 56 hours

Smartlead's times are plotted as time since the first failure. Its docs do not say whether the waits add up, and a help article on retries gives no counts at all. Warmerly's 10 sweeps are separate delivery runs, each with up to 3 attempts.

How a request carries the key

The same call, written the way each company's docs show it

WarmerlySmartlead
WarmerlyThe key travels in a header
curl https://app.warmerly.com/api/v1/accounts \
  -H "X-Api-Key: wmv_xxxxxxxx" \
  -H "X-Project-Id: <project id>"
  • Key shown once, starts with wmv_
  • Up to 10 active keys per user
  • No scopes: a key carries your full access
  • 60 requests a minute by default, never above 120
SmartleadThe key travels in the URL, or the body
curl "https://server.smartlead.ai/api/v1/campaigns/?api_key=YOUR_API_KEY"
  • Key shown once, query parameter recommended
  • Up to 25 admin keys, one shared rate pool
  • One key per client for white label setups
  • Resetting a key invalidates the old one at once

Examples are written from each company's own docs and are not tested calls. Smartlead also accepts the key as a body field on POST and PATCH. Neither documents scopes.

How Warmerly does it

Warmerly, in detail.

Platform API keys, the REST API and outbound webhooks are Agency only. The MCP server for AI assistants works on every plan.

01

Which plan gets the API

API keys, the API itself and webhooks need the Agency plan ($179 a month, 100 mailboxes). Free, Starter and Growth get a 403 agency_plan_required error. The 7-day Agency trial includes API access. The plan check follows the workspace the request acts on, so a key stops working after a downgrade and works again after an upgrade.

Warmerly product, checked 19 October 2026

02

Keys and what they can do

Keys start with wmv_, go in an X-Api-Key header to https://app.warmerly.com/api/v1 and are shown once. Each user can hold up to 10 active keys. A key carries the full access of the person who made it, with no per-endpoint scopes and no read-only keys.

Warmerly product, checked 19 October 2026

03

Rate limits

60 requests a minute per key by default, set between 1 and 120 at creation, and capped at 120 whatever the plan. Over the limit returns 429 too_many_requests. Lead search has an extra limit of 120 requests per 5 minutes per user. We found no separate hourly cap, so 60 a minute works out at most 3,600 an hour and the 120 setting at most 7,200 an hour.

Warmerly product, checked 19 October 2026

04

What the API covers

Reference pages exist for 12 areas: accounts (mailboxes), campaigns, leads, inbox, suppression, usage, email verification, email finder, warmup, workspaces, API keys and webhooks.

Warmerly product, checked 19 October 2026

05

Webhooks: 16 mailbox health events

Signed POSTs for mailbox health events such as score_drop, auth_fail, auto_paused and aged_in. They do not cover opens, clicks or replies. Agency only, with up to 10 subscriptions per user.

Warmerly product, checked 19 October 2026

06

Webhook delivery and signing

The X-Warmerly-Signature header is the hex-encoded HMAC-SHA256 of the raw body. Each delivery is tried up to 3 times (0.5 seconds, then 1 second, between attempts) and a failed event is not redelivered later. A subscription switches itself off after 10 consecutive sweeps in which a delivery failed, and PATCH re-enables it.

Warmerly product, checked 19 October 2026

07

MCP server on every plan

An MCP server at /api/mcp signs in with OAuth 2.1, needs no API key and works on every plan including Free. Reads and writes share 60 calls a minute per connection and no tool can start or resume campaign sending.

Warmerly product, checked 19 October 2026

08

Errors you will see

401 unauthorized for a missing, invalid or revoked key, 403 agency_plan_required when the plan is wrong, and 429 too_many_requests over the rate limit. Every error has a stable machine-readable code you can branch on. The errors page lists them all.

Warmerly product, checked 19 October 2026

09

Docs for machines too

The docs site publishes /llms.txt, /llms-full.txt and a Markdown copy of each page, generated from the same source as the web pages.

Warmerly product, checked 19 October 2026

How Smartlead does it

Smartlead, in detail.

A REST API with an API key, a webhooks API, published rate limits by tier, up to 25 admin keys plus client-level keys, and an MCP server. Its text pricing page shows API and webhooks on Pro and above.

01

Which plans get the API

The text version of the pricing page lists API and webhooks as No on Base and Yes on Pro, Unlimited Smart and Unlimited Prime. It says Pro is the first tier with CRM access, API and webhooks. The rendered pricing page did not make the main plan rows readable. The text version says prices were accurate as of 28 July 2026.

smartlead.ai/pricing.md · read 19 October 2026

02

Base URL and key

Requests go to https://server.smartlead.ai/api/v1. The key is generated at Settings, API Keys, and is shown once. The docs recommend an api_key query parameter, and allow an api_key field in the JSON body for POST and PATCH. Resetting a key invalidates the old one at once. An invalid key returns 401 UNAUTHORIZED.

api.smartlead.ai/authentication · read 19 October 2026

03

Rate limits by tier

The rate limits guide gives a Standard tier of 60 requests a minute, 1,000 an hour and 10 a second in bursts, and a Pro tier of 120 a minute, 3,000 an hour and 20 a second. Enterprise is custom. Three analytics and lead activity endpoints have their own limit of 10 requests per 60 seconds. Responses carry X-RateLimit-Limit, X-RateLimit-Remaining and X-RateLimit-Reset headers, and a 429 adds Retry-After. The guide does not say which of Base, Pro, Unlimited Smart and Unlimited Prime sits in which tier.

api.smartlead.ai/guides/rate-limits · read 19 October 2026

04

Admin keys and client keys

An account can hold up to 25 admin API keys, all sharing one rate limit pool, and the primary key cannot be revoked, only reset. Client-level keys are for white-label setups: one key per client, a default of 60 requests a minute that can be adjusted, and revoked keys kept for 30 days. Neither help article says which plan is needed.

helpcenter.smartlead.ai/en/articles/449-how-multiple-admin-api-keys-work-in-smartlead · read 19 October 2026

05

What the reference covers

The API index lists 27 unique endpoints in five sections: Campaigns (10), Email Accounts (4), Leads (8), Webhooks (4) and Analytics (2). POST /campaigns/{id}/leads appears under two sections with different descriptions, so the 28 listed entries are 27 unique ones. It also publishes guides, including webhook integration, error handling, rate limits and best practices.

api.smartlead.ai/llms.txt · read 19 October 2026

06

Webhooks: six events, three levels

EMAIL_SENT, EMAIL_OPENED, EMAIL_CLICKED, EMAIL_REPLIED, EMAIL_BOUNCED and EMAIL_UNSUBSCRIBED. A webhook can be set at user, client or campaign level, and a user-level one takes priority. Payloads carry fields such as campaign_id, lead_id and email_account_id, and replies carry the body.

api.smartlead.ai/core/webhooks · read 19 October 2026

07

Webhook retries and signing

Failed deliveries are retried after 1 minute, 5 minutes, 15 minutes, 1 hour and 6 hours, and a webhook is disabled after 5 failed attempts. The docs show an HMAC-SHA256 check but do not say which header holds the signature or where the secret comes from. Webhook deliveries are not subject to API rate limits.

api.smartlead.ai/core/webhooks · read 19 October 2026

08

MCP server

The home page describes 170 actions across campaigns, leads, analytics and inbox. The help article says MCP works in Claude Desktop only, over SSE, with the API key placed in the connection URL, and warns to treat the key like a password.

helpcenter.smartlead.ai/en/articles/300-smartlead-mcp-server · read 19 October 2026

09

Docs for machines too

The API docs publish an llms.txt index and Markdown copies of pages, and the help centre has two articles titled API Documentation and Full API Documentation.

api.smartlead.ai/llms.txt · read 19 October 2026

What Smartlead does not say

We looked, and found no statement on these. That is about its published pages only, not about the product.

  • Which of Smartlead's four plans sits in its Standard tier and which in its Pro tier for rate limits.
  • A definitive plan row for the API on the rendered pricing page: the ticks are images. We relied on the text version, dated 28 July 2026.
  • Which plans include client-level keys and multiple admin keys: neither help article says.
  • Whether an official SDK exists: not mentioned in the API index.
  • Which header carries the webhook signature and where the signing secret comes from.
  • Whether the MCP server is available on every plan.
The numbers

Only what we could verify.

API: Warmerly and Smartlead side by side. Warmerly is in the first column.
MeasureWarmerlySmartlead
APIAgency planListed as a plan feature; which plans include it is not readable on the pricing page
Plans, monthlyFree $0, Starter $19, Growth $49, Agency $179Base $39, Pro $94, Unlimited Smart $174, Unlimited Prime $379
Plan needed for the APIAgency, $179 a month (also the 7-day Agency trial)Pro, $94 a month, per pricing text; not on Base
Plan needed for webhooksAgencyPro and above, per pricing text
Rate limit a minute60 by default per key, 1 to 120 set at creation, never above 12060 on its Standard tier, 120 on its Pro tier; Enterprise custom
Hourly capNone found; 60 a minute is at most 3,600 an hour, 120 a minute at most 7,2001,000 an hour on Standard, 3,000 on Pro
Burst limitNot stated10 a second on Standard, 20 a second on Pro
Where the key goesX-Api-Key headerapi_key query parameter, or a body field on POST and PATCH
Keys per accountUp to 10 active per userUp to 25 admin keys, plus one key per client
Key scopesNone, a key carries your full accessNo scopes documented; a client key is limited to one client
Webhook events16, all about mailbox health6 campaign events: sent, opened, clicked, replied, bounced, unsubscribed
Webhook delivery tries3 attempts, then not redelivered; off after 10 failed sweepsRetries after 1 minute, 5 minutes, 15 minutes, 1 hour and 6 hours; off after 5 failed attempts
Webhook signingHMAC-SHA256 in X-Warmerly-SignatureHMAC-SHA256 in its example; header and secret location not documented
MCP serverEvery plan, OAuth 2.1, 60 calls a minuteClaude Desktop over SSE with an API key; 170 actions claimed
Documented surface12 reference areas (units differ, see text)27 unique endpoints in 5 sections
In practice

What it means for you.

Our reading of the facts above. Not a promise, and not the only reasonable reading.

1

Smartlead's entry point is lower

Our reading: if its pricing text is right, API access starts at $94 on Pro, against $179 for Warmerly Agency. The Agency trial is the cheap way to test Warmerly's API.

2

Smartlead's limits are written down in more detail

Our reading: Smartlead publishes hourly caps, bursts, headers and a per endpoint limit. Warmerly publishes 60 a minute per key and a ceiling of 120, with no hourly cap found. For heavy syncs you can plan around Smartlead's numbers more precisely.

3

Smartlead's webhooks suit CRMs

Our reading: replies, opens and unsubscribes as events are what a CRM sync needs. Warmerly's webhooks tell you a mailbox score dropped, which is a different job.

4

Keys: more choice on one side, simpler on the other

Our reading: Smartlead has up to 25 admin keys and per client keys for agencies. Warmerly has up to 10 keys, each with your full access. Neither documents scopes. A key in a URL query string can show up in server logs, so use a header or body where you can.

5

Warmerly's MCP route is open to everyone

Our reading: a Free user can still connect Claude or ChatGPT through MCP without an API key, though it cannot start sending. Smartlead's MCP setup needs your API key, so a plan that includes the API.

6

Test the tier your plan lands in

Our reading: Smartlead does not say which plan is on its Standard tier. If you rely on 120 a minute, check with support before you buy.

Who it suits

Pick the one that fits.

Warmerly

Warmerly is the better fit if

  • You are on Agency anyway, or want a 7-day trial to test the API.
  • You want an MCP connection on a lower plan, with OAuth rather than a key.
  • You want mailbox health alerts pushed to your own system.
Smartlead

Smartlead is the better fit if

  • You want API and campaign webhooks from around $94 a month.
  • You need reply and open events in a CRM or script.
  • You want client-level API keys for agency work, or published hourly limits to plan around.
Questions
Which Warmerly plan includes the API?

Agency, $179 a month, which also includes the 7-day Agency trial. API keys and webhooks are Agency only, but the MCP server is on every plan.

Which Smartlead plan includes the API?

Pro, $94 a month, per its pricing text, and not Base at $39. Its rendered pricing page does not show this clearly.

What are the API rate limits?

Warmerly defaults to 60 a minute per key, set from 1 to 120. Smartlead publishes 60 a minute and 1,000 an hour on Standard, 120 a minute and 3,000 an hour on Pro.

How is the API key sent?

Warmerly uses an X-Api-Key header. Smartlead uses an api_key query parameter, or a body field on POST and PATCH.

Sources

Smartlead pages were read on 19 October 2026. Plans and wording change, so check the vendor's own page before you decide. Warmerly details come from the product as it runs today.

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