Your history stops
disappearing.
Home Assistant purges its detailed history after ten days. Four PLCs and no historian is worse. Send yours here instead: full resolution for 14 days to 2 years by plan, and hourly min/max/average for 10 years on every plan, including the free one.
Incl. VAT is the price for consumers in Sweden. The VAT on your own invoice is worked out at checkout from your billing address and, for a business, its VAT number. 30-day free trial on Pro for new subscribers — card required, not charged if you cancel before day 30.
No signup needed · sample data
The managed historians we found, Canary's and TDengine's, start at $970 a month and sell no fewer than 3,500 tags. Hosted services that cost less do exist, and the comparison lists them, each with its source. Tag Historian keeps 10 years of hourly history on every plan, Free included, stores it in Sweden, and charges one flat monthly price per plan, chosen by how many tags you keep. Here are the prices, with sources.
Whatever you already run
Every way in and every way out is on every plan, the free one included, except that alerts reach your own signed webhook from Pro up, and Excel reports and read-only chart links are on Pro and Business. Email, push and chat alerts are on Free too. Beyond that, plans differ in scale.
Home Assistant
Install the Tag Historian integration through HACS and pick entities in a dialog, with your tag quota in view. It sends each entity's unit, imports the history the recorder already holds, and follows an entity you rename. No HACS? Home Assistant's own InfluxDB integration sends here too.
MQTT
A collector runs next to your broker and connects outward - no port forwarding, no broker exposed. Mosquitto, zigbee2mqtt, Tasmota.
OPC UA
Subscribe to the PLC tags you list - secured endpoints (Basic256Sha256), typed values with exact OPC UA quality codes, and disk buffering when the uplink drops. Beta.
InfluxDB line protocol & REST
POST /api/v2/write accepts line protocol unchanged, so Telegraf and any InfluxDB v2 client writes without modification. Plus a REST batch API and Azure IoT Hub.
10 years of hourly history - on every plan
Full resolution for 14 days on Free, 1 year on Pro, 2 years on Business. After that the individual readings go and the hourly min/max/average/count for every tag stays for 10 years. Nothing is parked offline: a five-year chart comes back from the day tier in about 1 800 points.
Deadband compression
Store a reading when it moves by more than the deadband, and at least once an hour regardless. Stored points are 22 bytes each: timestamp, typed value, the full 32-bit OPC UA status code and a per-record checksum.
Alerts that reach a person
Threshold, rate-of-change and silent-sensor rules with a delay and a reset margin, so a noisy signal raises one alert instead of one per wobble and the alert closes itself when the value comes back. A reading held up by a network outage still raises its alert, saying when it happened; the readings a replayed buffer delivered before its newest, and a backfill, page nobody. Alerts go to email, ntfy, Pushover, Telegram, Slack and Microsoft Teams on every plan, Free included, and every account's "no data" rules email its owner by default. Without any rule, the owner is also emailed when a source that has been sending stops, and an account that is sending data gets a short summary of its week every Monday. A failed send is retried for about an hour, and the Explorer shows which alerts did not get through. From Pro, a webhook signed HMAC-SHA256 over timestamp and body.
Query, stream, export, share
A REST API for history, a WebSocket subscription for values as they arrive, an official Python client for scripts and cron jobs (installed from github.com/softi-dev/tag-historian-clients — not yet on PyPI), and exports of measurements, aggregates and tag metadata as Parquet, CSV or JSON. No export fee and no proprietary step in the middle. On Pro and Business, an Excel report to send on: the tags and period you pick, a row per hour or per day with minimum, maximum and average, in your time zone. And a read-only link that shows one saved chart to someone without an account — a plant manager, a customer — under names you choose, until it expires or you revoke it.
Hosted in Sweden
Azure Sweden Central, with a nightly backup to a geo-redundant vault whose offsite copy sits in the paired Swedish region. Every file is written under your own customer id, and a request for someone else's data is refused rather than filtered. Invite as many people as you like, on every plan, Free included, each as Viewer, Editor or Admin. Dashboard sign-in takes a code from an authenticator app if you want it to - or if your team's Admin says everyone must.
Four Simple Steps
From sensor to insight. Hobbyists to industrial scale.
Connect
Home Assistant via the Tag Historian integration from HACS, or its own InfluxDB integration without it; OPC UA, MQTT, Sparkplug B and Modbus TCP via a collector on your own network; Azure IoT Hub, or the REST API. Pick whichever you already run.
Ingest
Send measurements with timestamps, batched or streaming. A 2xx means the reading is committed to the write-ahead log, not merely received. If the buffer ever fills you get 503 with Retry-After - never a silent drop.
Store
Deadband compression into a compact binary format. Full resolution for 14 days to 2 years depending on plan - hourly min/max/average/count then stays for 10 years on every plan, including Free.
Use it
Charts and dashboards in the app, a REST API for your own tools, a WebSocket subscription for live values, threshold alerts, and exports to Parquet, CSV or JSON whenever you want out.
Priced by tag, not by reading
A tag is one series — one Home Assistant entity, one MQTT topic, one OPC UA node. Cost follows how many series you keep, not how often you sample them.
Home Assistant, MQTT, OPC UA, Sparkplug B, Modbus TCP, REST, line protocol, dashboards and exports are on every plan, the free one included, and so are alerts in the app and by email, ntfy, Pushover, Telegram, Slack and Microsoft Teams. Every account is also emailed when a source stops sending and, while it sends data, gets a short summary of its week every Monday. Plans differ in scale, in Excel reports and read-only chart links, which are on Pro and Business, and in one place an alert can go: your own signed webhook, from Pro up.
Prices are in euro, billed monthly, and shown excluding VAT, with the price for consumers in Sweden, 25% VAT included, beneath. The VAT on your invoice is calculated at checkout from your billing address and, for a business, its VAT number.
Free
Enough to point a real system at it and see whether any of this is worth paying for.
- 5 tags
- 50k readings/day
- 14 days at full resolution
- 10 years of hourly history
- Unlimited team members, as Viewer, Editor or Admin
- Alerts by email, push and chat
- Email support, direct to the developer
Pro
A house, a boat, a workshop, or one machine on a line.
€11.25/month incl. 25% VATfor consumers in Sweden
30-day free trial on Pro for new subscribers — card required, not charged if you cancel before day 30
- 50 tags
- 500k readings/day
- 1 year at full resolution
- 10 years of hourly history
- Unlimited team members, as Viewer, Editor or Admin
- Alerts by email, push, chat and signed webhook
- Excel reports: hourly or daily min, max and average
- Read-only chart links to share without an account
- Email support, direct to the developer
Business
A small plant: several machines, a boiler house, a few hundred signals.
€111.25/month incl. 25% VATfor consumers in Sweden
- 500 tags
- 5M readings/day
- 2 years at full resolution
- 10 years of hourly history
- Unlimited team members, as Viewer, Editor or Admin
- Alerts by email, push, chat and signed webhook
- Excel reports: hourly or daily min, max and average
- Read-only chart links to share without an account
- Email support, direct to the developer
Enterprise
More tags than Business, a contractual SLA, or something the standard plans do not cover.
What that conversation usually covers
- Tag limits beyond 500
- A retention window that matches your reporting obligations
- What uptime we can commit to in writing, and what it costs
- Getting your data out of whatever it is in today
Not sure which of these you need — or whether you need any of them? What the alternatives cost and whether Home Assistant already does this for free.
Questions people ask before they send us anything
- How much does Tag Historian cost?
- Free is €0 for 5 tags. Pro is €9 a month for 50 tags. Business is €89 a month for 500 tags. Prices are in euro, billed monthly and exclude VAT; a consumer in Sweden pays €11.25 for Pro or €111.25 for Business, including 25% VAT. 30-day free trial on Pro for new subscribers — card required, not charged if you cancel before day 30. Every plan, the free one included, takes as many team members as you invite, each as Viewer, Editor or Admin.
- How long is my data kept?
- Individual readings are kept at full resolution for 14 days on Free, 1 year on Pro and 2 years on Business. After that window the individual readings are deleted but the hourly minimum, maximum, average and count for every tag remain for 10 years — on every plan, including the free one.
- What is a tag?
- One tag is one series: one Home Assistant entity, one MQTT topic, one OPC UA node, or one field of one Telegraf metric. Plans are priced by tag count rather than by how many readings you send, because storage cost tracks the number of series, not the sample rate.
- How do I get data in?
- Home Assistant through the Tag Historian integration, installed through HACS, or without HACS through its built-in influxdb integration; Telegraf through outputs.influxdb_v2; MQTT, OPC UA, Sparkplug B and Modbus TCP through a collector you run on your own network; Azure IoT Hub; or a REST batch API. Anything that speaks the InfluxDB v2 write endpoint works unchanged.
Start Free
5 tags. 50,000 readings a day. 14 days at full resolution, and 10 years of hourly history. No credit card.
You land in Tag Historian Explorer already signed in, with the first step for each way in: Home Assistant, the collector for OPC UA, MQTT, Sparkplug B and Modbus TCP, or the HTTP API. Every guide is here too, and names the scope its API key needs.