API response format — JSON schema and pagination

Every REST API has three shape decisions that determine whether the client code will be pleasant or miserable: the envelope, the pagination model, and the error format. This page is the reference for all three, with a JSON Schema fragment you can paste into your OpenAPI generator.

Response envelope

Every JSON response — success or error — has the same top-level shape:

{
  "data":  <object | array | null>,
  "error": <object | null>,
  "meta":  <object>
}

On success, data is populated and error is null. On failure, the reverse. meta is always present and always contains at least a requestId.

Success example

{
  "data": {
    "id": "t_01H9XABC4D5E6F7G8H",
    "status": "complete",
    "summary": { "inboxCount": 18, "spamCount": 3, "missingCount": 1, "total": 22 }
  },
  "error": null,
  "meta": {
    "requestId":        "req_01H9X7KEYABCDEF",
    "creditsRemaining": 248,
    "version":          "2026-07-01"
  }
}

Error example

{
  "data": null,
  "error": {
    "code":    "validation_error",
    "message": "Field 'from' must be a valid email address",
    "field":   "from",
    "docs":    "https://check.live-direct-marketing.online/docs/errors#validation_error"
  },
  "meta": {
    "requestId": "req_01H9X7KEYBADBEEF",
    "version":   "2026-07-01"
  }
}

Status code map

Pagination — cursor-based

Every list endpoint uses forward-only cursor pagination. You pass ?limit=N&cursor=..., and receive meta.nextCursor (or null) plus a Link header with rel="next".

GET /api/tests?limit=50

200 OK
Link: <https://check.live-direct-marketing.online/api/tests?limit=50&cursor=eyJpZCI6InRfMDEifQ==>; rel="next"

{
  "data": [ /* 50 test objects */ ],
  "error": null,
  "meta": {
    "nextCursor": "eyJpZCI6InRfMDEifQ==",
    "hasMore":    true,
    "requestId":  "req_..."
  }
}

Why cursor, not page?

Page-based pagination breaks when items are inserted or deleted mid-walk — you can either miss items or see duplicates. Cursor pagination is stable under concurrent writes and is the model every serious REST API has converged on over the last decade.

The cursor is opaque — do not try to base64-decode it or sort by it. Treat it as a "continue reading here" token and nothing more.

Test object schema

{
  "id":              "t_01H9XABC4D5E6F7G8H",
  "status":          "complete",
  "createdAt":       "2026-07-03T11:02:14Z",
  "completedAt":     "2026-07-03T11:03:42Z",
  "from":            "hello@news.yourbrand.com",
  "subject":         "Weekly digest #42",
  "summary": {
    "inboxCount":    18,
    "spamCount":      3,
    "missingCount":   1,
    "total":         22
  },
  "auth":            { "spf": "pass", "dkim": "pass", "dmarc": "pass" },
  "spamAssassinScore": 1.2,
  "rspamdScore":       0.8,
  "providers":       [ /* per-seed detail */ ],
  "dnsbl":           [ /* blacklist check results */ ],
  "screenshots":     [ /* screenshot URLs */ ],
  "metadata":        { /* opaque tenant metadata */ }
}

Provider result sub-object

{
  "provider":  "gmail",
  "folder":    "inbox",
  "folderRaw": "INBOX",
  "tookMs":    4120,
  "headersUrl": "https://check.live-direct-marketing.online/r/t_.../headers.txt",
  "screenshotUrl": "https://check.live-direct-marketing.online/r/t_.../gmail.png"
}

folder is normalised to a small enum: inbox, spam, promotions, updates, social, missing, other. folderRaw is the provider-native label for debugging.

SPF / DKIM / DMARC sub-object

{
  "spf": {
    "result": "pass",
    "record": "v=spf1 include:_spf.google.com include:sendgrid.net ~all",
    "domain": "news.yourbrand.com"
  },
  "dkim": {
    "result":   "pass",
    "selector": "s1",
    "domain":   "news.yourbrand.com",
    "keySize":  2048
  },
  "dmarc": {
    "result":   "pass",
    "policy":   "quarantine",
    "alignment": { "spf": "pass", "dkim": "pass" }
  }
}

DNSBL sub-object

[
  { "list": "zen.spamhaus.org",    "listed": false },
  { "list": "bl.spamcop.net",      "listed": false },
  { "list": "b.barracudacentral.org", "listed": false },
  { "list": "dnsbl.sorbs.net",     "listed": true, "reason": "dynamic IP range" }
]

Screenshot URL lifecycle

Screenshot URLs are signed and time-limited. They survive as long as the test is within its retention window (30 days on free, 12 months on Starter, 24 on Growth), then return 404. The URL does not change — there is no rotation — so you can bookmark or embed it as long as the test is in retention.

Do not hotlink screenshots into tenant UI long-term. Download them and rehost if you need longer retention than your plan provides.

Timestamps — ISO 8601, always UTC

Every timestamp the API returns is ISO 8601, in UTC, with a trailing Z. Example: 2026-07-03T11:02:14Z. No other format is ever returned; no timezone offsets other than Z; no epoch seconds; no microseconds.

Render in the user's local timezone on your frontend using whatever library you already have. Never assume a server-side format change.

JSON Schema fragment

Paste this into your OpenAPI generator. It covers the envelope and the test object with enum-validated fields.

{
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "$id":     "https://check.live-direct-marketing.online/schema/test.json",
  "type":    "object",
  "required": ["data", "error", "meta"],
  "properties": {
    "data": {
      "oneOf": [
        { "type": "null" },
        {
          "type": "object",
          "required": ["id", "status", "createdAt"],
          "properties": {
            "id":         { "type": "string", "pattern": "^t_[A-Z0-9]{26}$" },
            "status":     { "enum": ["pending", "running", "complete", "cancelled", "failed"] },
            "createdAt":  { "type": "string", "format": "date-time" },
            "completedAt":{ "type": "string", "format": "date-time" },
            "from":       { "type": "string", "format": "email" },
            "subject":    { "type": "string", "maxLength": 998 },
            "summary": {
              "type": "object",
              "required": ["inboxCount", "spamCount", "missingCount", "total"],
              "properties": {
                "inboxCount":   { "type": "integer", "minimum": 0 },
                "spamCount":    { "type": "integer", "minimum": 0 },
                "missingCount": { "type": "integer", "minimum": 0 },
                "total":        { "type": "integer", "minimum": 0 }
              }
            },
            "auth": {
              "type": "object",
              "properties": {
                "spf":   { "enum": ["pass", "fail", "neutral", "softfail", "none"] },
                "dkim":  { "enum": ["pass", "fail", "none"] },
                "dmarc": { "enum": ["pass", "fail", "none"] }
              }
            }
          }
        }
      ]
    },
    "error": {
      "oneOf": [
        { "type": "null" },
        {
          "type": "object",
          "required": ["code", "message"],
          "properties": {
            "code":    { "type": "string" },
            "message": { "type": "string" },
            "field":   { "type": "string" },
            "docs":    { "type": "string", "format": "uri" }
          }
        }
      ]
    },
    "meta": {
      "type": "object",
      "required": ["requestId"],
      "properties": {
        "requestId":        { "type": "string" },
        "creditsRemaining": { "type": "integer" },
        "nextCursor":       { "type": "string" },
        "hasMore":          { "type": "boolean" },
        "version":          { "type": "string" }
      }
    }
  }
}

Frequently asked questions