Drawing on the Chart: Horizontal Lines and Trendlines Across Every Symbol

You drew a trendline on BTC-PERP two weeks ago. You've drawn the same trendline four times since because the chart tool resets every time you refresh the page. Each redraw is slightly different because you're eyeballing anchor points from scratch instead of refining the one you'd committed to. The result: your "level" moves around based on when you last happened to be looking at the chart, which is the opposite of what a level is supposed to do.

Horizontal lines and trendlines are now live on every JTX chart — desktop and mobile — and they persist per-symbol in device storage. Draw them once, they're there next week.

What's in

Two drawing tools, accessible from a small toolbar on the top-right of the chart:

• Horizontal line — click the icon, click the chart at your target price, done. The line stretches across the full chart width at that price, with a small price label on the right edge. Drag the label up or down to adjust the price without redrawing.
• Trendline — click the icon, click once at the first anchor, click again at the second. The line extends between the two anchors; you can drag either endpoint to re-anchor without losing the other.

Both tools apply colour based on the asset-class accent (crypto green, forex blue, commodities amber, indices violet) so lines on different symbols don't blur together when you flip between charts. Each line is clickable — tap it and a small controls strip appears with delete, hide (greyed-out instead of removed), and lock (prevents accidental drag). Hidden lines live in a per-symbol dropdown so you don't lose them; locked lines persist through accidental taps during trade entry.

Persistence

The core of why this matters: everything is stored in your browser's IndexedDB, keyed by `(symbol, user_id)`. Draw a line on BTC-PERP, and the next time you open BTC-PERP on the same browser profile, the line is there. Flip between symbols all day and your levels stay put per-symbol — BTC-PERP's levels don't leak onto ETH-PERP.

The storage is local. We don't sync drawings across devices right now; a line drawn on your laptop doesn't appear on your phone and vice-versa. Cross-device sync is on the roadmap and is a non-trivial design question (do we sync hidden lines? Do we overwrite when timestamps collide? Should sync be opt-in?) that we'd rather solve properly than ship with the wrong defaults. For now, drawings are device-local.

Clearing browser data clears drawings. Export/import is also on the roadmap — the current workaround is to screenshot your chart with the lines visible, which actually turns out to be surprisingly rare as a need because most traders only maintain active drawings on symbols they're trading today.

Mobile

Same two tools on the mobile app, driven by tap gestures:

• Tap the drawing icon in the top-right of the chart to enter drawing mode.
• Tap the chart once for horizontal, tap-and-release-tap for trendline anchors.
• Long-press any existing line to open the controls strip.
• Pinch-to-zoom and pan still work; drawing mode doesn't lock out gestures.

The persistence model is the same — drawings live in device storage. The web and mobile stores are separate because they're different browser engines.

Why this is a bigger deal than it sounds

Technical analysis is 20% identifying the level and 80% waiting for the price to come back to it. Without persistent drawings, the "waiting" part becomes "re-identifying the level every time I log in", which contaminates the entire process — your level is now a function of what the chart looked like most recently, which is the information you were trying to filter out.

With persistent drawings, you can:

• Set a level once, revisit it a month later. The anchor is identical to what you decided when you were calm and had time to think. No contamination from recent price action.
• See when a level broke in retrospect. The horizontal you drew in July is still on the chart in October. If BTC crossed it in August and respected it as resistance in September, you can see that story.
• Build a durable level library per symbol. Over a trading quarter, your BTC-PERP chart accumulates maybe 5-15 meaningful horizontal lines (prior swing highs, round numbers that got defended, Fibonacci clusters you drew once). You stop re-deriving them every session.

The feature that enables this is boring. The workflow change it enables is substantial.

What's next

Not everything shipped in this phase. Still on the roadmap:

• Fibonacci retracements — likely next. Three-anchor tool, standard 23.6/38.2/50/61.8/78.6 levels, optional extensions.
• Rectangle and arrow annotations — for marking consolidation ranges and highlighting specific candles.
• Text annotations — "earnings 2026-Q3", "FOMC pause", short labels you want pinned to a time/price coordinate.
• Cross-device drawing sync — mentioned above. Would mean a server-side store, which means per-user quotas and an export/import pathway. Open design question.

Each adds a bit of chart-as-notebook capability without turning the chart into a drawing app that forgets it's also a trading tool. The order of what we build next will depend on what traders actually use and what they ask for.

Access

• On the web app, reload the chart on any symbol and the drawing toolbar appears top-right.
• On mobile, update to the latest version from the Play Store or TestFlight and the drawing icon shows up on the chart screen.

Available on every one of the 293 instruments. If you have an account, nothing else to do; if you don't yet, open one and the chart tooling is included.