canonical: https://jentic.com/apis/blynk.io/blynk

# Blynk Cloud Device HTTPS API

Jentic publishes the only available OpenAPI specification for Blynk Cloud Device HTTPS API, keeping it validated and agent-ready. Blynk is an IoT platform with mobile and web dashboards, and the Device HTTPS API lets external systems read and write datastream values, log custom events, query historical data, and check whether a hardware device is currently online. Datastreams are the named virtual pins (V0, V1, etc.) that hardware writes to and dashboards read from. Authentication is per-device - each call carries a token query parameter scoped to a single Blynk device.

## For AI agents

Read and write Blynk datastream values, log device events, and check hardware connectivity for IoT devices on Blynk Cloud.

## Scope

Does not provision new devices, manage user accounts, or build mobile dashboards - use for read/write access to datastream values, event logging, and connectivity checks on existing Blynk devices only.

## Capabilities

- Read the current value of a datastream by virtual pin name
- Write a single datastream value to update device state
- Update multiple datastreams at once with the batch endpoint
- Log a custom named event against a device with optional description
- Pull historical datastream data for charting and analytics
- Check whether a device is currently connected to Blynk Cloud

## Use cases

### Remote device control from a backend

Control a Blynk-connected device (relay, motor, light, plug) from a backend service or workflow engine without going through the Blynk mobile app. GET /update with the token, the datastream pin name, and the value triggers the device to act on the new value the next time it polls. GET /batch/update accepts multiple pin/value pairs in one call. Suitable for home automation hooks, scheduled actuator triggers, and remote support tools.

Example prompt: Call GET /update?token={token}&V0=1 to turn on a relay wired to virtual pin V0 on the target device.

### Sensor data collection

Pull current and historical sensor values from devices reporting into Blynk for analytics or dashboards outside Blynk. GET /get returns the current value of a datastream, and GET /data returns the historical series with a configurable time window. Useful when an external time-series database, Grafana board, or analytics warehouse is the system of record.

Example prompt: Call GET /data?token={token}&dataStream=V1&period=1d to pull the last 24 hours of temperature readings from datastream V1.

### Connectivity health check

Detect dropouts by checking whether a Blynk device is currently connected to the cloud. GET /isHardwareConnected returns a simple boolean for the device the token belongs to. Combine with /logEvent to record an event when a watchdog detects a sustained dropout, useful for fleet ops dashboards and alerting pipelines.

Example prompt: Call GET /isHardwareConnected?token={token} and, if false, call GET /logEvent?token={token}&code=offline_alert to record the dropout.

### AI agent IoT command assistant

Let an AI agent take simple actions against Blynk-connected hardware on behalf of a user - turning a plug on or off, setting a thermostat target, or pulling a sensor reading. The agent searches Jentic for the right Blynk operation by intent, loads the schema, and executes with the device token held in your Jentic One instance. Suitable for voice-driven smart home assistants and chat-based IoT control prototypes.

Example prompt: Search Jentic for 'turn on a Blynk device', load the schema for GET /update, and execute it with token and V0=1 to turn the device on.

## Key endpoints

| Method | Path | Description |
| --- | --- | --- |
| GET | /get | Read the current value of a datastream |
| GET | /update | Update a single datastream value |
| GET | /batch/update | Update multiple datastreams in one call |
| GET | /data | Pull historical datastream values |
| GET | /logEvent | Log a custom event against the device |
| GET | /isHardwareConnected | Check whether the device is online |

## Key resources

- **Datastream get** — Read the current value of a virtual pin
- **Datastream update** — Write a value to a virtual pin, single or batch
- **Data history** — Historical datastream values with a configurable time window
- **Events** — Log custom named events against a device
- **Connectivity** — Check whether a device is currently online

## Why Jentic

- **Setup:** Wiring the Blynk Cloud API by hand means passing its device token as a query parameter, keeping it out of your own logs, and picking the right server address. Through Jentic you install once, import Blynk from the API Directory, store the token once, and your agent calls it.
- **Permission scoping:** The Blynk device token itself binds every call to a single device, and the operation targets travel in query parameters rather than the URL path, so limit the agent to the operations it needs, such as reading a datastream or checking connectivity. You choose that set, so writing values with update or batch update is not included unless you add it.
- **Credential handling:** Your Blynk device token is stored once, encrypted, by your own Jentic One instance and injected at execution time. It never enters the agent's prompt, logs, or context.
- **Discovery method:** Agents search Jentic by intent such as 'read a Blynk datastream value' or 'check if a Blynk device is connected', and Jentic returns the matching operation with its input schema so the agent calls the right endpoint without browsing the docs.

## Related APIs

- **Blues Notehub API** — Cellular IoT platform with fleet management - heavier-weight than Blynk for Wi-Fi/BLE prosumer devices
- **Blues Notehub API** — Sister Blues listing - broader IoT management for cellular fleets
- **Blockchain Data API** — Pair when IoT devices should react to confirmed Bitcoin transactions

## FAQ

### Why is there no official OpenAPI spec for Blynk Cloud Device HTTPS API?

Blynk publishes a developer documentation site but does not distribute a maintained OpenAPI 3 file. Jentic generates and maintains this spec so AI agents and developers can call the Blynk Device HTTPS API via standard tooling. It is validated against the live API and kept up to date. Get started with Jentic One, the self-hosted execution layer.

### What authentication does the Blynk Device HTTPS API use?

Each call requires a device-scoped token passed as a query parameter (?token=...). The token is generated when a device is provisioned in Blynk and is unique per device. Through Jentic, the token is stored in the encrypted vault and injected at execution time, so the agent never handles the raw value, and per-device tokens stay isolated.

### Can I write to multiple datastreams in one call?

Yes. GET /batch/update accepts multiple pin=value pairs in the query string (for example V0=1&V1=22.5&V2=on) so you can update several datastreams in a single request. This is more efficient than issuing repeated /update calls when several values change at once.

### What are the rate limits for the Blynk Device HTTPS API?

Blynk applies per-device and per-account rate limits not enumerated in the spec. The published guidance is to keep request volume modest (a few requests per second per device); HTTP 429 responses come back when the limit is exceeded. Heavier ingestion should use Blynk's MQTT interface instead.

### How do I read historical data through Jentic?

Search Jentic for 'pull Blynk datastream history', load the schema for GET /data, and execute it with the token, dataStream pin name, and a period (1h, 1d, 1w, 1m). Install with pip install jentic and call await client.execute(ExecutionRequest(...)). The response is a time-series array.

### Can I check whether a device is online?

Yes. GET /isHardwareConnected with the device token returns a boolean indicating current connectivity to Blynk Cloud. This is suitable for liveness checks, watchdog scripts, and dashboard indicators.

### Is the Blynk Cloud API free?

Blynk offers a free developer plan with limits on devices, datastream count, and history retention. Paid plans (Maker, Pro, Business) raise these limits and add features like white-label apps and on-prem deployment. The HTTPS API itself does not carry an additional fee.

### Can I limit what my agent is allowed to do with the Blynk Cloud Device HTTPS API?

Yes. Because you run Jentic One yourself, your own rules decide which Blynk operations the agent may call, so you can grant read-only access such as GET /get and GET /isHardwareConnected while withholding write operations like GET /update and GET /batch/update. The device token binds every call to a single Blynk device, and the operation targets travel in query parameters rather than the URL path, so the agent can only reach the endpoints you have allowed on that one device. You decide that set, and writing datastream values stays excluded unless you add those operations.