SuperTrend Signal Alerts (MetaTrader 5 and MetaTrader 4)

A free SuperTrend indicator that draws a two-colour trend line and one buy or sell arrow per trend flip, on closed bars only, and sends an alert for each arrow. Optional EMA and RSI filters apply to the arrows and alerts. Source for both editions, a Python reference of the maths, and the tests that were used to check that the MT5 and MT4 code, the Python reference and each other all agree.

Website: allanninal.dev/mql5 (indicators) · MT4 editions · allanninal.dev · Contact: message me on LinkedIn.

It is an indicator, not a strategy. It draws a line and arrows and places no trades. Nothing here is a profit claim (see Honest limits).

Get it on the MQL5 Market

Edition	Platform	Price	Link
SuperTrend Signal Alerts	MT5	free	https://www.mql5.com/en/market/product/201882
SuperTrend Signal Alerts MT4	MT4	free	https://www.mql5.com/en/market/product/202324

The Market builds are the same calculation as the source in this repository. There is no paid edition of this indicator: what you see here is the whole product.

Contents

1. What it is and who it is for
2. Why it was built
3. How it works
4. Non-repainting: the proof and how it was tested
5. Architecture and buffers
6. Inputs, alerts, install and compile
7. Run the Python reference and the tests
8. Honest limits
9. Free, with no paid edition
10. Licence and credits

What it is and who it is for

What: the SuperTrend method as a native MetaTrader indicator. Two bands sit multiplier x ATR above and below the bar's middle price and only ratchet in the direction of the trend. While price closes on one side, the line follows the band on that side. When a close breaks the opposite band the trend flips, the line jumps to the other band, and you get an arrow (buy below the candle, sell above) and an alert (pop-up, sound, push, e-mail). Two optional filters on the arrows and alerts: close above or below an EMA, and RSI above or below 50.

For: traders who follow trends and want the flip points marked on any symbol and timeframe, and who want to know that the arrow they saw will still be there tomorrow. Also for developers who want a small, tested indicator with documented buffers to read from an EA with iCustom.

Not for: anyone who expects early entries. A trend-following line turns after the move has started, and in sideways markets it can flip often.

Image notes: charts 01-03 are drawn by the Python reference on broker history (the same numbers the indicator shows); the alert text on 06 is the indicator's real text but the pop-up and phone card around it are mock-ups; the Data Window panel on 08 is a mock-up of the buffer map. They are illustrations, not terminal captures. MT4 versions are in docs/images/mt4/.

Why it was built

SuperTrend is one of the most widely used trend lines on TradingView, and traders who move to MetaTrader ask for it. The motivations, stated with the evidence we actually have:

• A native, readable port. The method is a few lines of arithmetic and does not need a closed-source box.
• Trust in the arrows. Our market research (demand scan of MQL5 Market, forums and freelance boards, October 2026) found repeated complaints about arrow indicators that repaint, and a 2026-07 request for "arrows confirmed on bar close". The design rule follows: an arrow is only drawn on a bar that has closed, and never moves afterwards.
• Honest scale of demand. The same research found that named classic indicators such as SuperTrend are requested only rarely by name (14 freelance requests in the board we counted, against several hundred for custom strategy work). So this is a free tool that gives a clean reference implementation and builds a track record, not a claim of mass demand.
• Provable behaviour. Every number in this README comes from an executed check, listed below, not from a promise.

mindmap
  root((SuperTrend Signal Alerts))
    Problem
      TradingView indicator, no clean MetaTrader port
      Arrow indicators that repaint
      Alerts that fire twice or during history load
    Design rules
      Signals on closed bars only
      One alert per bar
      Same maths on MT5 MT4 and Python
    Proof
      Python reference
      Bar by bar parity
      Tester repaint probe
      Market validation

How it works

The maths, step by step

Let O, H, L, C be the bar's open, high, low, close, i the bar index (oldest = 0), n the ATR period and m the multiplier.

1. True range

   TR[i] = max(H[i]-L[i], |H[i]-C[i-1]|, |L[i]-C[i-1]|), and TR[0] = H[0]-L[0].

2. ATR, one of two methods (input ATR method):

   • RMA / Wilder (default, same as ta.atr on TradingView): ATR[n-1] = mean(TR[0..n-1]), then ATR[i] = (ATR[i-1] * (n-1) + TR[i]) / n.
   • SMA of the true range: ATR[i] = mean(TR[i-n+1..i]).

3. Source src[i] = (H[i] + L[i]) / 2.

4. Raw bands up = src - m * ATR[i] and dn = src + m * ATR[i]. Let up1 and dn1 be the previous bar's final bands (on the first bar, the bar's own).

5. Ratchet (the bands only move with the trend):

   • if C[i-1] > up1: up = max(up, up1) (the lower band only rises)
   • if C[i-1] < dn1: dn = min(dn, dn1) (the upper band only falls)

6. Trend trend[i], starting at +1:

   • if trend = -1 and C[i] > dn1: trend = +1
   • if trend = +1 and C[i] < up1: trend = -1
   • otherwise unchanged

7. Line line[i] = up when trend = +1, else dn. Blue in an uptrend, red in a downtrend.

8. Signals (on closed bars only):

   • Buy: trend[i] = +1 and trend[i-1] = -1
   • Sell: trend[i] = -1 and trend[i-1] = +1
   • EMA filter: a buy also needs C[i] > EMA[i], a sell C[i] < EMA[i], where EMA is seeded with the average of the first p closes and then EMA[i] = EMA[i-1] + 2/(p+1) * (C[i] - EMA[i-1]).
   • RSI filter: a buy also needs RSI[i] > 50, a sell RSI[i] < 50, with Wilder's RSI (gains and losses smoothed with the same seeded RMA).

A comparison "close above band" ignores floating-point noise below 1e-10 of the band, in the indicator and in the Python reference alike: a band can tie a close exactly in real arithmetic, and a last-bit difference would otherwise decide a trend flip differently in two languages. The filters change arrows and alerts only, not the line. The live bar's line may move; arrows are never drawn on it.

Per-bar algorithm

flowchart TD
    A[New or updated bar i] --> B[src = high + low / 2]
    B --> C[True range, then ATR: Wilder RMA or SMA]
    C --> D{ATR available? i >= n-1}
    D -- no --> Z[No line, no arrow]
    D -- yes --> E[up = src - m x ATR, dn = src + m x ATR]
    E --> F[Ratchet: up only rises while the last close was above it<br/>dn only falls while the last close was below it]
    F --> G{trend = down and close > previous dn?}
    G -- yes --> H[trend = up]
    G -- no --> I{trend = up and close < previous up?}
    I -- yes --> J[trend = down]
    I -- no --> K[trend unchanged]
    H --> L[Line = up band, blue]
    J --> M[Line = dn band, red]
    K --> N[Line = band of the current trend]
    L --> O{Bar is closed and trend just flipped?}
    M --> O
    N --> O
    O -- no --> Z2[Line only, no arrow, no alert]
    O -- yes --> P{EMA and RSI filters pass?}
    P -- no --> Z2
    P -- yes --> Q[Arrow on the bar]
    Q --> R[Alert, once per bar, only when live]

Signal states

stateDiagram-v2
    [*] --> Warmup
    Warmup --> Uptrend: ATR ready, first bar trend is up
    Uptrend --> Uptrend: close stays above the lower band, band only rises
    Downtrend --> Downtrend: close stays below the upper band, band only falls
    Uptrend --> Downtrend: closed bar breaks the lower band (sell arrow, alert)
    Downtrend --> Uptrend: closed bar breaks the upper band (buy arrow, alert)
    Uptrend --> Downtrend: flip suppressed by a filter (line flips, no arrow)
    Downtrend --> Uptrend: flip suppressed by a filter (line flips, no arrow)

Alert flow

sequenceDiagram
    participant T as Terminal
    participant I as SuperTrend indicator
    participant H as Alert helper
    participant U as You
    T->>I: OnCalculate (history load, prev_calculated = 0)
    I->>H: signal on last closed bar? live = false
    H-->>I: ignored (never alert during history load)
    T->>I: OnCalculate (new bar closes, prev_calculated > 0)
    I->>I: recompute last bars, test the bar that just closed
    I->>H: SignalAlert(text, bar time, live = true)
    alt bar time is newer than the last alert and not in the tester
        H->>U: pop-up (optional sound, push, e-mail)
    else same bar again or tester run
        H-->>I: nothing sent
    end

What the multiplier does (measured)

A larger multiplier puts the bands further from price, so the trend flips later and less often. Arrows (buy plus sell) per month on closed bars of broker history, 2023-10-01 to 2026-10-12 (36.3 months), ATR period 10, other inputs default. Source: docs/data/arrows-per-month.json. This counts arrows only. It says nothing about profit.

xychart-beta
    title "H1 arrows per month by multiplier (EURUSD and XAUUSD)"
    x-axis ["1.5", "2.0", "2.5", "3.0", "4.0", "5.0"]
    y-axis "arrows per month" 0 --> 40
    line [33.3, 23.67, 17.61, 13.46, 8.94, 6.47]
    line [30.66, 21.63, 15.47, 11.78, 8.31, 5.94]

First line EURUSD, second XAUUSD.

xychart-beta
    title "Arrows per month by timeframe, multiplier 3.0 (XAUUSD)"
    x-axis ["M15", "H1", "H4", "D1"]
    y-axis "arrows per month" 0 --> 60
    bar [49.23, 11.78, 2.75, 0.47]

Non-repainting: the proof and how it was tested

"Non-repainting" is easy to claim. Here is what was actually run. Raw result files are in tests/results/.

1. Three implementations, compared bar by bar. The Python reference (tests/reference.py) was written from the TradingView script's behaviour, not translated from the MQL code. The MT5 and MT4 indicators were then dumped bar by bar (line, buy, sell buffers) in the MetaTrader Strategy Tester, and tests/check_parity.py compared each dump with the reference. Pass means: every closed bar's line within 1e-9 relative, and arrows on exactly the same bars.

	MT5	MT4
dumps compared	36 (4 symbols x M15/H1/H4 x 3 input sets)	37 (same 36 + one every-tick EURUSD H1)
bars compared	1,122,870	761,453
arrows compared (buy + sell)	30,823	22,525
result	ALL PASS	ALL PASS

Symbols: EURUSD, XAUUSD, GBPJPY, BTCUSD. Input sets: defaults; SMA ATR method with multiplier 2 and period 14; EMA and RSI filters on. Source: tests/results/parity-mt5-and-mt4.txt. The MT5 M15 dumps cover only 4,450 bars each (a short test history), and the MT4 test history is shorter on the FX pairs, which is why the bar counts differ.

xychart-beta
    title "Arrows compared, Python vs indicator (all 0 differences)"
    x-axis ["Defaults MT5", "SMA ATR MT5", "EMA+RSI MT5", "Defaults MT4", "SMA ATR MT4", "EMA+RSI MT4"]
    y-axis "arrows compared" 0 --> 18000
    bar [9014, 16893, 4916, 6667, 12260, 3598]

(MT4 "Defaults" is 6,514 arrows over 12 runs plus 153 in the every-tick run = 6,667.)

2. Repaint probe. An EA records which signal buffers are set on each bar at the moment it closes, then reads the same bars again at the end and counts any value that changed. It also counts any signal ever shown on the still-forming bar.

Run	Closed bars checked	Signals seen at close	Changed afterwards	Signals on the live bar
MT5, EURUSD H1, every tick, 10,411,052 ticks	4,644	126	0	0
MT4, 37 runs combined	756,852	22,449	0	0

Source: tests/results/repaint-summary.md. The MT5 repaint probe was run once (EURUSD H1, default inputs); the MT4 probe ran on every dump run.

3. Market validation. Both Market builds passed the MQL5 Market's automated product validation before publication (this is the Market's own check, not part of this repository).

flowchart LR
    R[reference.py<br/>Python, from the TradingView behaviour] --> P
    S5[MT5 indicator] --> T5[Tester script<br/>DumpIndicator<br/>every bar to CSV]
    S4[MT4 indicator] --> T4[Tester EA<br/>SuperTrendDump + Dump4.mqh<br/>CSV + repaint log]
    T5 --> P[check_parity.py<br/>line 1e-9, same arrows]
    T4 --> P
    S5 --> RP[RepaintProbe EA<br/>values at close vs final]
    T4 --> RL[repaint log<br/>per run]
    P --> V{all pass?}
    RP --> V
    RL --> V
    V -- yes --> M[Market validation]
    V -- no --> F[fix, rerun everything]

Why the design cannot repaint

• Arrows are written only when i <= rates_total - 2, i.e. never on the forming bar.
• Each bar's bands and trend depend only on that bar and earlier bars (recursive formulas, no look-ahead).
• Alerts fire only for the bar that just closed, only after the history load, once per bar, and never in the tester.
• What does move: the line on the forming bar, because the live bar's high, low and close change. That is not a signal.

Architecture and buffers

flowchart TB
    subgraph MT5["mql5/Indicators/SuperTrendSignalAlerts"]
        A5[SuperTrendSignalAlerts.mq5<br/>inputs, buffers, OnCalculate]
        B5[SignalAlerts.mqh<br/>alert inputs, TfName, SignalAlert]
        A5 -- include --> B5
    end
    subgraph MT4["mql4/Indicators/SuperTrendSignalAlerts"]
        A4[SuperTrendSignalAlerts.mq4]
        B4[SignalAlerts.mqh<br/>MT4 edition]
        A4 -- include --> B4
    end
    subgraph TESTS[tests]
        R[reference.py]
        C[check_parity.py]
        D5[mql5: DumpIndicator, RepaintProbe, Params.mqh]
        D4[mql4: SuperTrendDump.mq4, Dump4.mqh]
        C --> R
    end
    D5 -. iCustom/IndicatorCreate .-> A5
    D4 -. iCustom .-> A4

classDiagram
    class SuperTrendSignalAlerts {
        +InpATR int
        +InpMult double
        +InpMethod ENUM_ST_ATR
        +InpUseEMA bool
        +InpEMA int
        +InpUseRSI bool
        +InpRSI int
        +OnInit()
        +OnCalculate()
    }
    class SignalAlerts {
        +InpAlertPopup bool
        +InpAlertSound bool
        +InpAlertPush bool
        +InpAlertEmail bool
        +g_alert_last datetime
        +TfName()
        +SignalAlert()
    }
    class reference {
        +true_range()
        +sma()
        +rma()
        +ema()
        +rsi()
        +supertrend()
    }
    SuperTrendSignalAlerts --> SignalAlerts : alerts
    reference ..> SuperTrendSignalAlerts : same maths, compared by check_parity

iCustom buffer table (for EA developers)

Buffer	MT5	MT4
0	SuperTrend line (colour line)	SuperTrend line (not drawn; read this one)
1	colour index of the line (0 blue, 1 red)	blue half of the drawn line
2	Buy arrow price (bar low), empty otherwise	Buy arrow price, empty otherwise
3	Sell arrow price (bar high), empty otherwise	Sell arrow price, empty otherwise
4	trend EMA (when the filter is on)	red half of the drawn line
5	calculation buffer	trend EMA (when the filter is on)
6-12 (MT5) / 6-13 (MT4)	calculation buffers (bands, trend, ATR, EMA, RSI, gains, losses)	calculation buffers

Empty value is EMPTY_VALUE. Read arrows on closed bars (shift 1 and higher). iCustom parameters follow the input order: ATR period, ATR multiplier, ATR method, EMA filter, EMA period, show EMA, RSI filter, RSI period, show line, arrow gap, pop-up, sound, sound file, push, e-mail, debug. In MT5 the input group headings also count as string parameters when you build a handle with IndicatorCreate (see tests/mql5/Include/IndTest/Params.mqh).

Inputs, alerts, install and compile

Input	Default	Meaning
ATR period	10	Length of the ATR
ATR multiplier	3.0	Band distance in ATRs. Lower: flips sooner and more often. Higher: later
ATR method	RMA / Wilder	RMA (same as ta.atr) or SMA of the true range
Only signals with the EMA trend	false	Buy only above the EMA, sell only below
EMA period	200	Length of the trend EMA
Draw the EMA	true	Show the EMA when the filter is on
Buy only RSI above 50, sell only below	false	RSI filter on arrows and alerts
RSI period	14	Length of the RSI
Draw the SuperTrend line	true	Show or hide the line (arrows stay)
Arrow distance from the candle	12 px (MT5) / 0.3 x ATR (MT4)	Gap between arrow and candle
Pop-up alert	true	Terminal alert window
Play a sound / sound file	false / alert.wav	File from the terminal's Sounds folder
Push notification	false	Needs your MetaQuotes ID in Options
E-mail	false	Needs e-mail set up in Options
Debug log for bug reports	false	Writes extra lines to the Experts tab, to attach when you report a problem

Alert text: SuperTrend EURUSD H1: BUY, trend up from 1.08512.

Install from source. Copy mql5/Indicators/SuperTrendSignalAlerts/ into <terminal data folder>/MQL5/Indicators/ (MT5) or mql4/Indicators/SuperTrendSignalAlerts/ into <data folder>/MQL4/Indicators/ (MT4), open SuperTrendSignalAlerts.mq5 or .mq4 in MetaEditor and press Compile (F7). Both compile with 0 errors (checked on a Windows machine with MetaEditor; the compiled files are not in the repository). Keep the two files of each edition together: the indicator includes SignalAlerts.mqh from its own folder. The debug log needs the Chart Kit file as well: copy mql5/Include/ChartKit/ (MT5) or mql4/Include/ChartKit/ (MT4) into the Include folder of the data folder.

Run the Python reference and the tests

python3 -m venv .venv && . .venv/bin/activate && pip install -r requirements.txt

import sys; sys.path.insert(0, "tests")
import numpy as np
from reference import supertrend
# o, h, l, c are float arrays of OHLC bars, oldest first
line, buy, sell = supertrend(o, h, l, c, period=10, mult=3.0)   # buy/sell hold the arrow price or NaN

To repeat the parity check on your own data:

1. Compile the indicator and the test tool for your platform (tests/mql5/Scripts/DumpIndicator, or tests/mql4/SuperTrendDump.mq4 with tests/mql4/Include/IndTest4/Dump4.mqh in your MQL4/Include/IndTest4/; MT5 also needs tests/mql5/Include/IndTest/Params.mqh).
2. Run it in the Strategy Tester (MT4) or as a script (MT5) for each symbol and timeframe, with the input sets in tests/configs.tsv (MT5) / tests/mql4/configs.tsv (MT4). The tool writes one CSV per symbol and timeframe.
3. python3 tests/check_parity.py <folder with the CSVs>. It prints PASS or FAIL per file and an overall result (the file names must start with the tags st_default, st_sma_m2_p14, st_ema_rsi).
4. Repaint: run tests/mql5/Experts/RepaintProbe in the MT5 Strategy Tester (every tick); MT4 writes its repaint log with the dump.

The price dumps used for the published numbers are not in this repository (they are broker price data).

Honest limits

• An indicator signal is not a strategy. No stop-loss, position sizing or exit rules are provided or implied, and the arrows were not optimised or back-tested for profit. Whether a trend flip makes money depends on your market, costs and rules.
• No profit or accuracy claim is made. The only numbers here are about consistency (the three implementations agree, signals do not move) and frequency (arrows per month).
• Lag is built in. The line turns after the move has started; a higher multiplier turns later still.
• Sideways markets produce frequent flips; the EMA and RSI filters reduce some of them but not all.
• Data-dependent. ATR is seeded from the first bars in the terminal's history, so the very first arrows of a short history can differ from a longer one.
• Scope of the tests. Four symbols, three timeframes, three input sets, one MT5 repaint run. Other symbols and timeframes are not covered by the published numbers. The MT5 build was not run on a live chart as part of these numbers.

Free, with no paid edition

SuperTrend Signal Alerts has no paid sibling: the Market builds and this source are the same free indicator, with every input described above. Website: allanninal.dev/mql5 (MT4).

Licence and credits

Origin of the maths. SuperTrend is a trend-following indicator created by Olivier Seban. The TradingView "SuperTrend" script, which many traders know it by, is by KivancOzbilgic; it is open source on TradingView. Thank you to both.

What this means for the licence. TradingView publishes open-source scripts under the Mozilla Public License 2.0 unless the author states another licence. I did not confirm what licence the original script's header states, so I took the conservative route: the three files that implement the SuperTrend calculation are licensed MPL-2.0:

• mql5/Indicators/SuperTrendSignalAlerts/SuperTrendSignalAlerts.mq5
• mql4/Indicators/SuperTrendSignalAlerts/SuperTrendSignalAlerts.mq4
• tests/reference.py

They are independent implementations in other languages (the Python one written from the script's described behaviour, not translated), plus additions (closed-bar signals, alerts, EMA and RSI filters), but treating them as derived from an MPL-2.0 work is the safe reading. MPL-2.0 is file-level: changes to those files must stay MPL-2.0 and be shared.

Everything else (alert helper SignalAlerts.mqh, test tools, parity checker, docs, images) is © 2026 Allan Niñal under the PolyForm Noncommercial License 1.0.0: free for personal and other noncommercial use, not for commercial use (source-available, not OSI open source). Each source file has an SPDX-License-Identifier line. Texts: LICENSE, LICENSES/MPL-2.0.txt. The licence applies to this source, not to anything you build or trade with the indicator. Trading involves risk; the software is provided as is.

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Website: allanninal.dev/mql5 · MT4 · allanninal.dev · Questions: message me on LinkedIn.