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.
Getting data in
Pick the one you already run. Every plan includes every integration; plans differ in scale, not in features.
Home Assistant
Send Home Assistant history off the Pi with the built-in influxdb integration. Five lines of YAML, and the four settings that decide whether it works.
Home Assistant (HACS)
Install the Tag Historian custom integration through HACS: a config-flow picker instead of YAML, your tag quota visible live, and a Repairs card when something goes wrong.
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.
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 — and for the AI assistant you ask instead of opening a dashboard.
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 (MCP)
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).
Reference
The endpoint itself, and the two questions any serious evaluator asks before sending real data anywhere.
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, and the restore paths that have not been drilled.
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 — 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