Start a sajn Login session

Create a hosted login session and get a URL to send the user to.

Use this when you don’t want to run an OIDC client — typically a native app that opens loginUrl in an in-app browser.

Flow:

POST here to get loginUrl
Open it; the user authenticates with BankID on sajn’s hosted page
We redirect to your redirectUri with ?sessionId=… (and ?state=… if you sent one)
GET /api/v1/login/sessions/{id} from your server to read the result

The redirect is only a handle. Never trust it as proof of authentication — anyone can craft that URL. The server-side GET is the authoritative read, because it is authenticated as your organization.

redirectUri must be registered on the client. Custom schemes (myapp://auth) are supported so the in-app browser can dismiss straight back into your app.

POST

api

sessions

Start a sajn Login session

curl --request POST \
  --url https://app.sajn.se/api/v1/login/sessions \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "clientId": "cm4k2x9p10039abcd1234efgh",
  "redirectUri": "https://example.com/auth/callback",
  "state": "f9a1c2e3"
}
'

import requests

url = "https://app.sajn.se/api/v1/login/sessions"

payload = {
    "clientId": "cm4k2x9p10039abcd1234efgh",
    "redirectUri": "https://example.com/auth/callback",
    "state": "f9a1c2e3"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    clientId: 'cm4k2x9p10039abcd1234efgh',
    redirectUri: 'https://example.com/auth/callback',
    state: 'f9a1c2e3'
  })
};

fetch('https://app.sajn.se/api/v1/login/sessions', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://app.sajn.se/api/v1/login/sessions",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'clientId' => 'cm4k2x9p10039abcd1234efgh',
    'redirectUri' => 'https://example.com/auth/callback',
    'state' => 'f9a1c2e3'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://app.sajn.se/api/v1/login/sessions"

	payload := strings.NewReader("{\n  \"clientId\": \"cm4k2x9p10039abcd1234efgh\",\n  \"redirectUri\": \"https://example.com/auth/callback\",\n  \"state\": \"f9a1c2e3\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://app.sajn.se/api/v1/login/sessions")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"clientId\": \"cm4k2x9p10039abcd1234efgh\",\n  \"redirectUri\": \"https://example.com/auth/callback\",\n  \"state\": \"f9a1c2e3\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://app.sajn.se/api/v1/login/sessions")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"clientId\": \"cm4k2x9p10039abcd1234efgh\",\n  \"redirectUri\": \"https://example.com/auth/callback\",\n  \"state\": \"f9a1c2e3\"\n}"

response = http.request(request)
puts response.read_body

{
  "id": "cm4k2x9p10033abcd1234efgh",
  "status": "COMPLETED",
  "method": "SE_BANKID",
  "completedAt": "2026-09-29T07:41:00.000Z",
  "state": "f9a1c2e3",
  "sub": "sajn|7f3e1c92b4",
  "claims": {
    "sub": "sajn|7f3e1c92b4",
    "amr": [
      "SE_BANKID"
    ],
    "auth_time": 1790667660,
    "name": "Kai Lindqvist",
    "given_name": "Kai",
    "family_name": "Lindqvist",
    "birthdate": "1990-01-01",
    "nin": "191212121212",
    "nin_type": "SE_PERSONNUMMER"
  },
  "loginUrl": "https://login.sajn.se/l/cm4k2x9p10033abcd1234efgh/open",
  "expiresAt": "2026-10-28T22:00:00.000Z"
}

{
  "code": "VALIDATION_FAILED",
  "message": "Invalid input: expected string, received undefined",
  "userMessage": "Förfrågan innehåller ogiltiga värden.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2",
  "issues": [
    {
      "path": "clientId",
      "code": "INVALID_TYPE",
      "message": "Invalid input: expected string, received undefined"
    }
  ]
}

{
  "code": "UNAUTHORIZED",
  "message": "Invalid API token",
  "userMessage": "Ogiltig API-nyckel",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2"
}

{
  "code": "INSUFFICIENT_SCOPE",
  "message": "Insufficient OAuth scope: requires login:write",
  "userMessage": "Applikationen saknar behörighet (scope) för denna åtgärd.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2",
  "requiredScopes": [
    "login:write"
  ],
  "grantedScopes": [
    "profile:read"
  ]
}

{
  "code": "NOT_FOUND",
  "message": "Sajn Login session not found",
  "userMessage": "Resursen hittades inte.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2",
  "resource": "login_session"
}

{
  "code": "INVALID_STATE",
  "message": "The resource's current state doesn't allow the operation, such as editing a document that was already sent or downloading a file that isn't produced yet.",
  "userMessage": "Åtgärden är inte möjlig i resursens nuvarande status.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2"
}

{
  "code": "RATE_LIMITED",
  "message": "API rate limit exceeded",
  "userMessage": "För många förfrågningar. Försök igen om en stund.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2"
}

{
  "code": "INTERNAL_ERROR",
  "message": "Internal server error",
  "userMessage": "Något gick fel.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2"
}

{
  "code": "UPSTREAM_UNAVAILABLE",
  "message": "A service the operation depends on, such as an eID provider or a connected integration, failed or is unavailable. Retry with exponential backoff.",
  "userMessage": "En extern tjänst svarar inte just nu. Försök igen om en stund.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2"
}

Authorizations

Authorization

string

header

required

API key, e.g. Authorization: Bearer sajn_svc_.... Not scope-limited: acts with its owner's workspace role.

Scopes

Start sajn Login sessions.

Headers

Sajn-Version

enum<string>

API version for this request. Without it, the request uses the organization's default version; an organization without a default is pinned to the latest version by its first request.

Available options:

2026-09,

2026-10

Sajn-Workspace

string

ID of the workspace this request acts in, from GET /api/v1/workspaces. Without it, an API key acts in its default workspace. The token's user must be a member of the workspace; an OAuth token only accepts the workspace it was granted for. A workspace that doesn't exist or can't be reached returns 403 WORKSPACE_ACCESS_DENIED.

Idempotency-Key

string

Makes retries safe. A retry with the same key and the same request replays the stored response for 24 hours (header Idempotent-Replayed: true); the same key with a different request returns 400.

Maximum string length: 255

Body

application/json

Body

clientId

string

required

The sajn Login client to authenticate against.

Minimum string length: 1

redirectUri

string

required

Where to send the user when authentication finishes. Must be registered on the client.

Minimum string length: 1

state

string

Opaque value echoed back on the redirect and in the session result.

Maximum string length: 512

Response

200

string

required

The sajn Login session ID.

status

enum<string>

required

Available options:

PENDING,

COMPLETED,

FAILED,

EXPIRED

method

enum<string> | null

required

The eID the user authenticated with, such as SE_BANKID. Null until status is COMPLETED.

Available options:

SE_BANKID,

NO_BANKID_BIOMETRIC,

NO_BANKID_HIGH,

NO_QES,

DK_MITID,

DK_MITID_ERHVERV,

FI_FTN,

NL_IDIN,

ZEALID_QES,

null

completedAt

string<date-time> | null

required

state

string | null

required

sub

string | null

required

claims

object | null

required

The claims your client is approved for. A claim it isn't approved for is null.

Show child attributes

Open this in a browser or an in-app browser to authenticate the user. Set only in the response to the create request; null otherwise.

expiresAt

string<date-time> | null

required

When the user must have authenticated by. Set only in the response to the create request; null otherwise.

Start a sajn Login session

curl --request POST \
  --url https://app.sajn.se/api/v1/login/sessions \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "clientId": "cm4k2x9p10039abcd1234efgh",
  "redirectUri": "https://example.com/auth/callback",
  "state": "f9a1c2e3"
}
'

import requests

url = "https://app.sajn.se/api/v1/login/sessions"

payload = {
    "clientId": "cm4k2x9p10039abcd1234efgh",
    "redirectUri": "https://example.com/auth/callback",
    "state": "f9a1c2e3"
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

response = requests.post(url, json=payload, headers=headers)

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({
    clientId: 'cm4k2x9p10039abcd1234efgh',
    redirectUri: 'https://example.com/auth/callback',
    state: 'f9a1c2e3'
  })
};

fetch('https://app.sajn.se/api/v1/login/sessions', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

<?php

$curl = curl_init();

curl_setopt_array($curl, [
  CURLOPT_URL => "https://app.sajn.se/api/v1/login/sessions",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'clientId' => 'cm4k2x9p10039abcd1234efgh',
    'redirectUri' => 'https://example.com/auth/callback',
    'state' => 'f9a1c2e3'
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://app.sajn.se/api/v1/login/sessions"

	payload := strings.NewReader("{\n  \"clientId\": \"cm4k2x9p10039abcd1234efgh\",\n  \"redirectUri\": \"https://example.com/auth/callback\",\n  \"state\": \"f9a1c2e3\"\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(string(body))

}

HttpResponse<String> response = Unirest.post("https://app.sajn.se/api/v1/login/sessions")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"clientId\": \"cm4k2x9p10039abcd1234efgh\",\n  \"redirectUri\": \"https://example.com/auth/callback\",\n  \"state\": \"f9a1c2e3\"\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://app.sajn.se/api/v1/login/sessions")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"clientId\": \"cm4k2x9p10039abcd1234efgh\",\n  \"redirectUri\": \"https://example.com/auth/callback\",\n  \"state\": \"f9a1c2e3\"\n}"

response = http.request(request)
puts response.read_body

{
  "id": "cm4k2x9p10033abcd1234efgh",
  "status": "COMPLETED",
  "method": "SE_BANKID",
  "completedAt": "2026-09-29T07:41:00.000Z",
  "state": "f9a1c2e3",
  "sub": "sajn|7f3e1c92b4",
  "claims": {
    "sub": "sajn|7f3e1c92b4",
    "amr": [
      "SE_BANKID"
    ],
    "auth_time": 1790667660,
    "name": "Kai Lindqvist",
    "given_name": "Kai",
    "family_name": "Lindqvist",
    "birthdate": "1990-01-01",
    "nin": "191212121212",
    "nin_type": "SE_PERSONNUMMER"
  },
  "loginUrl": "https://login.sajn.se/l/cm4k2x9p10033abcd1234efgh/open",
  "expiresAt": "2026-10-28T22:00:00.000Z"
}

{
  "code": "VALIDATION_FAILED",
  "message": "Invalid input: expected string, received undefined",
  "userMessage": "Förfrågan innehåller ogiltiga värden.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2",
  "issues": [
    {
      "path": "clientId",
      "code": "INVALID_TYPE",
      "message": "Invalid input: expected string, received undefined"
    }
  ]
}

{
  "code": "UNAUTHORIZED",
  "message": "Invalid API token",
  "userMessage": "Ogiltig API-nyckel",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2"
}

{
  "code": "INSUFFICIENT_SCOPE",
  "message": "Insufficient OAuth scope: requires login:write",
  "userMessage": "Applikationen saknar behörighet (scope) för denna åtgärd.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2",
  "requiredScopes": [
    "login:write"
  ],
  "grantedScopes": [
    "profile:read"
  ]
}

{
  "code": "NOT_FOUND",
  "message": "Sajn Login session not found",
  "userMessage": "Resursen hittades inte.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2",
  "resource": "login_session"
}

{
  "code": "INVALID_STATE",
  "message": "The resource's current state doesn't allow the operation, such as editing a document that was already sent or downloading a file that isn't produced yet.",
  "userMessage": "Åtgärden är inte möjlig i resursens nuvarande status.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2"
}

{
  "code": "RATE_LIMITED",
  "message": "API rate limit exceeded",
  "userMessage": "För många förfrågningar. Försök igen om en stund.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2"
}

{
  "code": "INTERNAL_ERROR",
  "message": "Internal server error",
  "userMessage": "Något gick fel.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2"
}

{
  "code": "UPSTREAM_UNAVAILABLE",
  "message": "A service the operation depends on, such as an eID provider or a connected integration, failed or is unavailable. Retry with exponential backoff.",
  "userMessage": "En extern tjänst svarar inte just nu. Försök igen om en stund.",
  "requestId": "req_V1StGXR8Z5jdHi6BmyT2"
}

Get started

Core concepts

Guides

Webhooks

API fundamentals

Upgrading

sajn Login

API reference

Start a sajn Login session

Authorizations

Scopes

Headers

Body

Response