Docs
Every ingestion path, written as the configuration that works plus the two or three things that catch people out. All of it applies on the free plan — 5 tags, €0, no card, except Excel reports and read-only chart links, which are on Pro and Business.
Getting data in
Pick the one you already run. Every way in is on every plan, the free one included — what the plans change is how much you can send and keep.
Home Assistant
The Tag Historian integration, installed through HACS: pick entities in a dialog with your tag quota in view, import the history the recorder already holds, keep a tag through an entity rename, and get a Repairs card when something goes wrong.
Home Assistant without HACS
Home Assistant's own InfluxDB integration, pointed at Tag Historian: a dialog under Devices & services, a short YAML filter, and the four settings that decide whether it works.
Leave InfluxDB, keep the history
Keep your InfluxDB, or drop the server without losing the years you have: a resumable copy of the history, the switch of live data, and a Grafana dashboard by entity.
Telegraf
Point a stock Telegraf outputs.influxdb_v2 at Tag Historian, and prune the inputs first.
MQTT
Run a collector next to your broker — Mosquitto, zigbee2mqtt, Tasmota. Topic mapping, payload shapes, and what happens at the tag quota.
OPC UA (beta)
Subscribe to PLC tags from a collector inside the plant network. Security policies, quality codes, and no inbound firewall rule.
Sparkplug B (beta)
Subscribe to a Sparkplug B namespace on your own MQTT broker. One edge node can announce hundreds of metrics, so: filters, a tag budget, the full list of what it announced before you collect any of it, and nothing published but a rebirth request, plus host STATE if you set HostId.
Modbus TCP (beta)
Poll energy meters, older PLCs and RTU gateways from the same collector. 40001 is Address 0, word order, scaling, a CSV tag list, and what happens when a device stops answering.
Looking at it
Stored data you cannot see is a backup, not a historian. There is a chart in the app; this is for the dashboard you already have on the wall, the AI assistant you ask instead of opening a dashboard, and the spreadsheet or the read-only chart you send to someone who has neither.
Grafana
Chart your tags in Grafana today — Grafana Cloud free included — through Grafana Labs' own Infinity data source. The six settings, one panel, a tag dropdown, and why a long time range is showing you averages.
Claude and other AI assistants over MCP (beta)
Ask an AI assistant about your own tags — an MCP server for Claude Desktop and any MCP-compatible host. Read-only by default: it can list tags, read history and aggregates, and check alerts; write tools stay off unless you explicitly enable them. Installed from github.com/softi-dev/tag-historian-clients (not yet on PyPI).
Excel reports
A spreadsheet to send on: the tags and period you pick, a row per hour or per day with minimum, maximum, average and readings, in your time zone with summer time handled. On Pro and Business.
Share a chart by link
Send a plant manager or a customer a read-only chart of one saved view: no account, only the tags you chose under names you give them, until it expires or you revoke it. On Pro and Business.
Being told
Nobody watches a chart at three in the morning. When a value crosses a limit or a source goes quiet, the alert has to find a person — by email, on a phone, or in the chat they already read.
Reference
The endpoint itself, and the three questions any serious evaluator asks before sending real data anywhere: how long it is kept, where it lives, and how it is protected.
InfluxDB line protocol
POST /api/v2/write, every status code it returns, how lines become tag names, and where it deliberately is not InfluxDB.
How long data is kept
Full resolution per plan, hourly summaries for ten years on every plan including Free, and what a downgrade does.
Where your data lives
Both RPO numbers, the nightly vaulted backup, the daily database copy, and which restore paths have been drilled.
Security
Where data lives, encryption, sign-in and API keys, how the service is built and run, your rights to export and erase, and how to report a vulnerability. Including what we do not do yet.
Deciding whether to use this at all
Written to be useful even if the answer is no. Two of these three pages will tell some readers they do not need us.
What a data historian actually costs
Canary, TDengine, Ignition, Timebase, Grafana Cloud, TagoIO, emoncms.org — real published prices, each cited and dated.
Home Assistant long-term storage
What HA already keeps forever for free, and the three cases where that is not enough. Includes the case for doing nothing.
A historian for forty tags
Every tag-metered historian package starts at 3,500 tags. What to do when you have one machine.
Something missing?
These pages come from documentation written for the product rather than for search, so they cover what exists and stop where it stops. If a page is wrong, out of date, or silent about the thing you needed, say so — a correction is worth more to us than a signup.
support@taghistorian.com