Agent local API reference

The ERP Sync agent runs a small HTTP API on the computer where it is installed. You can use it to check the agent’s status, read its recent log entries, and pause, resume or trigger syncing from a script or a monitoring tool. This is the agent’s local API. It is not Omnilinker’s cloud API and it is not reachable from the internet. For calling Omnilinker itself, see the Developers section.

Base URL

http://localhost:5555

The port comes from the LocalApiPort setting in the agent’s appsettings.json (default 5555). Leave it at the default: the tray app’s fallback connection and the web app’s Local Service tab always use port 5555. See the configuration reference. The API uses plain HTTP. It is served by the Windows service, so it is available only while the service is running.

Access and security

Localhost only. The agent listens on the loopback addresses only (127.0.0.1 and ::1). Other computers on your network cannot connect to it, and it needs no firewall rule. A request that names any host other than localhost or a loopback address is refused with 403 Forbidden.
One required header. Every request to a route under /api must carry the header X-Omnilinker-Local: 1. Without it, the agent answers 403 Forbidden with an empty body. /health does not check the header; sending it there does no harm.
Browsers: Omnilinker only. A web page cannot add that header without asking the agent first (a CORS preflight). The agent agrees only for Omnilinker’s own address, https://omnilinker.pl, and its subdomains, over HTTPS. That is how the web app’s Local Service tab, open in a browser on the agent computer, reads the API. Requests from any other website are refused with 403.
No authentication. Programs on the computer, such as the tray app, PowerShell or curl, send the header and need no API key, password or token.

Invoke-RestMethod -Headers @{ "X-Omnilinker-Local" = "1" } http://localhost:5555/api/sync/status

Anyone who can run a program on the agent computer can call the API. They can read the agent’s status and log entries, and pause, resume or trigger syncing. The API does not check the Omnilinker ERP Sync Operators group that the tray app uses. It never returns the API key, the ERP password or the connection string, and it cannot change the agent’s settings. Still, treat access to the agent computer as access to the agent: limit who can sign in to it.

Conventions

Request and response bodies are JSON. Property names are camelCase.
Times are in UTC, in ISO 8601 format, for example 2026-09-27T08:15:02.1234567Z.
Enumerations are returned as numbers, not names. The tables on this page list the values.
Control routes return 400 Bad Request with a command response when the agent refuses the command.
403 Forbidden with an empty body means the request was refused before it reached the agent: the X-Omnilinker-Local header is missing, the host is not localhost, or a browser sent it from another website.
The examples use PowerShell. In Windows PowerShell 5.1, curl is an alias for Invoke-WebRequest. Type curl.exe to use curl.

Routes

Method	Route	Purpose
`GET`	`/health`	Health of the agent and its connections, as plain text.
`GET`	`/api/sync/health`	Liveness check: is the API answering.
`GET`	`/api/sync/status`	Full status of the agent.
`GET`	`/api/sync/config`	Agent version, state and whether it is paused.
`POST`	`/api/sync/now`	Ask the agent to look for changes now.
`POST`	`/api/sync/trigger`	Same as `/api/sync/now`.
`POST`	`/api/sync/pause`	Pause syncing.
`POST`	`/api/sync/resume`	Resume syncing.
`GET`	`/api/sync/logs`	Recent entries of the agent’s sync log.
`GET`	`/api/sync/outbox/stats`	Counts of events in the agent’s outbox.
`GET`	`/api/sync/hash/status`	State of hash-based change detection.
`GET`	`/api/sync/hash/stats`	Size of the agent’s hash store.
`POST`	`/api/sync/hash/trigger`	Start a hash check now.

No other routes exist.

Health

GET /health

Runs the agent’s health checks and returns the overall result as plain text: Healthy, Degraded or Unhealthy. The HTTP status is 200 OK for Healthy and Degraded, and 503 Service Unavailable for Unhealthy.

Check	Healthy	Degraded	Unhealthy
Local database	The agent’s local database answers.		It does not.
ERP connection	The agent is connected to the ERP database.		It is not.
SQL connection	The agent is connected to the ERP database.	The ERP database is not configured yet.	It is configured but not connected.
Cloud connection	Omnilinker (`omnilinker.pl`) answers.	Omnilinker answers with an error.	Omnilinker cannot be reached.

/health returns Unhealthy until the agent has connected to the ERP database, for example right after the service starts or before the setup wizard has run. Use /api/sync/health to check only that the service is running.

Invoke-WebRequest -Headers @{ "X-Omnilinker-Local" = "1" } http://localhost:5555/health -UseBasicParsing |
  Select-Object StatusCode, Content

GET /api/sync/health

Returns 200 OK whenever the API is answering. It does not check the ERP or Omnilinker.

string

Always healthy.

string

The agent’s current time, UTC.

curl -H "X-Omnilinker-Local: 1" http://localhost:5555/api/sync/health

{ "status": "healthy", "timestamp": "2026-09-27T08:15:02.1234567Z" }

Status

GET /api/sync/status

Returns the agent’s full status. The tray app’s status window and the web app’s Local Service tab show the same data.

integer

The agent’s state.

Value	State	Meaning
`0`	Idle	Ready, waiting for the next cycle.
`1`	Syncing	A sync is running, or a `POST /api/sync/now` request is waiting to be picked up.
`2`	Paused	Syncing is paused.
`3`	Error	The last cycle failed. See `lastError`.
`4`	Starting	The service is starting and has not loaded its configuration yet.
`5`	Stopping	The service is shutting down.

boolean

Whether the agent’s last request to Omnilinker succeeded.

boolean

Whether the agent is connected to the ERP database.

string | null

When the last sync cycle finished successfully.

string | null

When the next cycle is expected, if known.

integer

Errors since the last successful cycle.

string | null

The last error message, for example Waiting for cloud configuration.

string | null

Why a cycle is delayed, for example Product polling delayed (HashCheck in progress).

integer[]

Fixes the tray app offers for the last error. 1 test ERP connection, 2 test cloud connection, 3 check settings, 4 retry now, 5 view logs, 6 check network, 7 contact support, 8 view details, 9 skip item.

object

Events in the agent’s outbox, with pending, sent, failed and retrying. The same numbers as /api/sync/outbox/stats.

object

Outbox counts per entity type, keyed by type name (for example Product, Brand, PriceLevel, Price, Warehouse, Stock). Each value has total, synced, pending and failed. Only events still in the local outbox are counted: sent events are removed after 24 hours (1 hour during the initial sync).

string

The agent’s version.

boolean

Not used: always false. The agent updates itself, but does not report a waiting update here.

string | null

Not used: always null.

object | null

The same object as /api/sync/hash/status.

object | null

While a hash check runs: productsChecked, totalProducts, brandsChecked, totalBrands, elapsed, estimatedTimeRemaining and itemsPerSecond.

object | null

currentPending, healthLevel (0 normal, fewer than 50 pending; 1 elevated, 50 to 199; 2 backlogged, 200 or more), trend (0 steady, 1 growing, 2 draining), trendItemsPerMinute and trendDescription.

object[]

Operations running now, such as polling or publishing, with their item counts and progress.

object[]

The most recently completed operations, with completedAt, itemCount, duration, success and errorMessage.

object

Health of four components: erpConnection, cloudApi, database and credentials. Each has a level (0 healthy, 1 warning, 2 critical), a message and the time of the last check. overallHealth is the worst of the four, and issueCount counts those that are not healthy.

The objects under currentOperations, recentActivity and systemHealth also carry display fields used by the tray app. Do not rely on their exact shape; it can change between agent versions.

$status = Invoke-RestMethod -Headers @{ "X-Omnilinker-Local" = "1" } http://localhost:5555/api/sync/status
$status | Select-Object state, isConnected, isErpConnected, lastSyncTime, lastError
$status.outbox

A shortened response:

{
  "state": 0,
  "isConnected": true,
  "isErpConnected": true,
  "lastSyncTime": "2026-09-27T08:15:02.1234567Z",
  "nextSyncTime": null,
  "errorCount": 0,
  "lastError": null,
  "waitingReason": null,
  "suggestedActions": [],
  "outbox": { "pending": 0, "sent": 245, "failed": 0, "retrying": 0 },
  "entityCounts": {
    "Product": { "total": 240, "synced": 240, "failed": 0, "pending": 0 },
    "Brand": { "total": 5, "synced": 5, "failed": 0, "pending": 0 }
  },
  "version": "<agent version>",
  "updateAvailable": false,
  "updateVersion": null
}

GET /api/sync/config

Returns a few facts about the agent. It does not return its settings or credentials.

string

The agent’s version.

boolean

Whether syncing is paused.

string

The agent’s state as a name, for example Idle (unlike /api/sync/status, which returns a number).

Invoke-RestMethod -Headers @{ "X-Omnilinker-Local" = "1" } http://localhost:5555/api/sync/config

Control

These routes take no parameters and no request body.

Command response

Every control route, and POST /api/sync/hash/trigger, returns this object:

boolean

Whether the agent accepted the command.

string

What happened, or why the command was refused.

POST /api/sync/now

Asks the agent to look for changes now. POST /api/sync/trigger does exactly the same. The request is picked up at the agent’s next polling cycle, within PollingIntervalSeconds (60 seconds by default). With hash scan change detection it starts a hash check.

HTTP status	`message`	When
`200`	`Sync started`	Accepted.
`400`	`Sync is paused. Resume first.`	Syncing is paused.
`400`	`Sync is already in progress.`	A sync is running or a request is already waiting.

Invoke-RestMethod -Method Post -Headers @{ "X-Omnilinker-Local" = "1" } http://localhost:5555/api/sync/now

curl -X POST -H "X-Omnilinker-Local: 1" http://localhost:5555/api/sync/now

POST /api/sync/pause

Pauses syncing. The agent stops detecting new changes until you resume. Always returns 200 with Sync paused.

Events already in the outbox are still sent to Omnilinker while the agent is paused.
A pause is not kept when the service restarts.

Invoke-RestMethod -Method Post -Headers @{ "X-Omnilinker-Local" = "1" } http://localhost:5555/api/sync/pause

POST /api/sync/resume

Resumes syncing. Always returns 200 with Sync resumed.

Invoke-RestMethod -Method Post -Headers @{ "X-Omnilinker-Local" = "1" } http://localhost:5555/api/sync/resume

Logs

GET /api/sync/logs

Returns the newest entries of the agent’s own sync log, newest first. These are the entries the tray app’s log viewer shows. They are not the Omnilinker sync log entries described in Monitoring, and not the service’s log files.

integer

default:"50"

How many entries to return. At most 500; larger values return 500.

string

Minimum level: Debug, Info, Warning, Error or Critical (or 0 to 4). Returns entries at this level and above.

string

Only entries of this category, for example ErpPolling, HashCheck or ChangeConsumption. Exact match.

string

Only entries for this entity type. Exact match.

The response is an array of log entries:

integer

The entry’s ID.

string

When the entry was written.

integer

0 Debug, 1 Info, 2 Warning, 3 Error, 4 Critical.

string

The message.

string | null

Extra details, if any.

string | null

The component that wrote the entry.

string | null

The entity type concerned, if any.

string | null

The entity concerned, if any.

string | null

The exception, for errors.

Invoke-RestMethod -Headers @{ "X-Omnilinker-Local" = "1" } "http://localhost:5555/api/sync/logs?count=20&level=Warning" |
  Format-Table timestamp, level, category, message

curl -H "X-Omnilinker-Local: 1" "http://localhost:5555/api/sync/logs?count=20&level=Warning"

Outbox

GET /api/sync/outbox/stats

The agent queues every change in a local outbox and sends it to Omnilinker in batches. This route counts the events in the outbox by state.

integer

Waiting to be sent, including events that failed an attempt and will be tried again.

integer

Sent successfully and not yet cleaned up. Sent events are removed after 24 hours (1 hour during the initial sync).

integer

Failed on every attempt (MaxRetryAttempts, 5 by default). The agent does not send these again.

integer

Being sent right now. Despite the name, this is not a count of events waiting for a retry: those are in pending.

Invoke-RestMethod -Headers @{ "X-Omnilinker-Local" = "1" } http://localhost:5555/api/sync/outbox/stats

{ "pending": 5, "sent": 1245, "failed": 0, "retrying": 0 }

A pending count that keeps growing means the agent cannot send to Omnilinker. See Troubleshooting.

Hash check

A hash check compares the ERP data with what the agent last sent, to find changes. It is how the agent detects changes with hash scan change detection. See Wapro.

GET /api/sync/hash/status

boolean

Whether hash checks are enabled in the connection’s sync configuration. With WFM_INT change tracking, a weekly reconciliation check always runs and this is true.

boolean

Whether a hash check is running now.

boolean

Whether hash checks are paused on their own (from the tray app).

string | null

When the last hash check finished.

string | null

When the next one is due.

integer

Products compared in the last check. lastProductsChanged, lastBrandsChecked and lastBrandsChanged work the same way.

integer

Products in the hash store. totalStoredBrandHashes is the same for brands.

string | null

The last hash check error.

Invoke-RestMethod -Headers @{ "X-Omnilinker-Local" = "1" } http://localhost:5555/api/sync/hash/status

GET /api/sync/hash/stats

integer

Products in the hash store.

integer

Brands in the hash store.

string | null

When the store was last updated by a hash check.

Invoke-RestMethod -Headers @{ "X-Omnilinker-Local" = "1" } http://localhost:5555/api/sync/hash/stats

POST /api/sync/hash/trigger

Starts a hash check now, without waiting for its interval.

HTTP status	`message`	When
`200`	`Hash check started`	Accepted.
`400`	`Hash check is disabled in cloud configuration. Enable it in the web dashboard.`	Hash checks are disabled in the connection’s sync configuration.
`400`	`Hash check is already running. Wait for current check to complete or cancel it first.`	A check is running.

Invoke-RestMethod -Method Post -Headers @{ "X-Omnilinker-Local" = "1" } http://localhost:5555/api/sync/hash/trigger

Named pipe

The tray app talks to the service mainly over a Windows named pipe, OmnilinkerErpSync, and falls back to this HTTP API when the service does not answer on the pipe. The pipe is an internal interface between the two parts of the agent, not a public API: its commands can change between agent versions. Use the HTTP routes on this page for scripts and monitoring.

Who can connect: SYSTEM, administrators, and people signed in to the computer, at the console or over Remote Desktop.
What they can do: anyone connected can read the status, logs and settings. Commands that change the agent, its ERP database or its credentials, or that pause it, need a member of Omnilinker ERP Sync Operators or an administrator whose tray app runs elevated. Others get the error “Only an administrator of this PC can do that.” (code Pipe:NotAllowed). See Who can change the agent.
Which service: the tray app talks only to the Windows service. It does not trust another program that opens a pipe with the same name.

Get started

Set up

Configure sync

Operate

Providers

Reference

Agent local API reference

Base URL

Access and security

Conventions

Routes

Health

GET /health

GET /api/sync/health

Status

GET /api/sync/status

GET /api/sync/config

Control

Command response

POST /api/sync/now

POST /api/sync/pause

POST /api/sync/resume

Logs

GET /api/sync/logs

Outbox

GET /api/sync/outbox/stats

Hash check

GET /api/sync/hash/status

GET /api/sync/hash/stats

POST /api/sync/hash/trigger

Named pipe

​Base URL

​Access and security

​Conventions

​Routes

​Health

​GET /health

​GET /api/sync/health

​Status

​GET /api/sync/status

​GET /api/sync/config

​Control

​Command response

​POST /api/sync/now

​POST /api/sync/pause

​POST /api/sync/resume

​Logs

​GET /api/sync/logs

​Outbox

​GET /api/sync/outbox/stats

​Hash check

​GET /api/sync/hash/status

​GET /api/sync/hash/stats

​POST /api/sync/hash/trigger

​Named pipe

Base URL

Access and security

Conventions

Routes

Health

GET /health

GET /api/sync/health

Status

GET /api/sync/status

GET /api/sync/config

Control

Command response

POST /api/sync/now

POST /api/sync/pause

POST /api/sync/resume

Logs

GET /api/sync/logs

Outbox

GET /api/sync/outbox/stats

Hash check

GET /api/sync/hash/status

GET /api/sync/hash/stats

POST /api/sync/hash/trigger

Named pipe