diff --git a/Cargo.toml b/Cargo.toml
index c026295..f9304d5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -7,4 +7,5 @@ members = [
   "metrics-exporter-tcp",
   "metrics-exporter-prometheus",
   "metrics-tracing-context",
+  "metrics-observer",
 ]
diff --git a/metrics-observer/Cargo.toml b/metrics-observer/Cargo.toml
new file mode 100644
index 0000000..54990ae
--- /dev/null
+++ b/metrics-observer/Cargo.toml
@@ -0,0 +1,25 @@
+[package]
+name = "metrics-observer"
+version = "0.1.0"
+authors = ["Toby Lawrence <toby@nuclearfurnace.com>"]
+edition = "2018"
+
+license = "MIT"
+
+[dependencies]
+getopts = "0.2"
+bytes = "0.5"
+crossbeam-channel = "0.4"
+prost = "0.6"
+prost-types = "0.6"
+tui = "0.12"
+termion = "1.5"
+hdrhistogram = "7.1"
+evmap = "10.0"
+chrono = "0.4"
+metrics = { version = "0.13.0-alpha.5", path = "../metrics" }
+metrics-util = { version = "0.4.0-alpha.3", path = "../metrics-util" }
+
+[build-dependencies]
+prost-build = "0.6"
+built = "0.4"
\ No newline at end of file
diff --git a/metrics-observer/build.rs b/metrics-observer/build.rs
new file mode 100644
index 0000000..066cbe3
--- /dev/null
+++ b/metrics-observer/build.rs
@@ -0,0 +1,9 @@
+fn main() {
+    println!("cargo:rerun-if-changed=proto/event.proto");
+    let mut prost_build = prost_build::Config::new();
+    prost_build.btree_map(&["."]);
+    prost_build
+        .compile_protos(&["proto/event.proto"], &["proto/"])
+        .unwrap();
+    built::write_built_file().unwrap();
+}
diff --git a/metrics-observer/proto/event.proto b/metrics-observer/proto/event.proto
new file mode 100644
index 0000000..82280de
--- /dev/null
+++ b/metrics-observer/proto/event.proto
@@ -0,0 +1,28 @@
+syntax = "proto3";
+
+import "google/protobuf/timestamp.proto";
+
+package event.proto;
+
+message Metric {
+  string name = 1;
+  google.protobuf.Timestamp timestamp = 2;
+  map<string, string> labels = 3;
+  oneof value {
+    Counter counter = 4;
+    Gauge gauge = 5;
+    Histogram histogram = 6;
+  }
+}
+
+message Counter {
+  uint64 value = 1;
+}
+
+message Gauge {
+  double value = 1;
+}
+
+message Histogram {
+  uint64 value = 1;
+}
diff --git a/metrics-observer/src/input.rs b/metrics-observer/src/input.rs
new file mode 100644
index 0000000..04b628e
--- /dev/null
+++ b/metrics-observer/src/input.rs
@@ -0,0 +1,40 @@
+use std::io;
+use std::thread;
+use std::time::Duration;
+
+use crossbeam_channel::{bounded, Receiver, TrySendError, RecvTimeoutError};
+use termion::event::Key;
+use termion::input::TermRead;
+
+pub struct InputEvents {
+    rx: Receiver<Key>,
+    handle: thread::JoinHandle<()>,
+}
+
+impl InputEvents {
+    pub fn new() -> InputEvents {
+        let (tx, rx) = bounded(1);
+        let handle = thread::spawn(move || {
+            let stdin = io::stdin();
+            for evt in stdin.keys() {
+                if let Ok(key) = evt {
+                    // If our queue is full, we don't care.  The user can just press the key again.
+                    if let Err(TrySendError::Disconnected(_)) = tx.try_send(key) {
+                        eprintln!("input event channel disconnected");
+                        return;
+                    }
+                }
+            }
+        });
+
+        Self { rx, handle }
+    }
+
+    pub fn next(&mut self) -> Result<Option<Key>, RecvTimeoutError> {
+        match self.rx.recv_timeout(Duration::from_secs(1)) {
+            Ok(key) => Ok(Some(key)),
+            Err(RecvTimeoutError::Timeout) => Ok(None),
+            Err(e) => Err(e),
+        }
+    }
+}
\ No newline at end of file
diff --git a/metrics-observer/src/main.rs b/metrics-observer/src/main.rs
new file mode 100644
index 0000000..6dea223
--- /dev/null
+++ b/metrics-observer/src/main.rs
@@ -0,0 +1,154 @@
+use std::{error::Error, io};
+
+use chrono::Local;
+use termion::{event::Key, input::MouseTerminal, raw::IntoRawMode, screen::AlternateScreen};
+use tui::{
+    backend::TermionBackend,
+    layout::{Constraint, Direction, Layout},
+    style::{Color, Modifier, Style},
+    text::{Span, Spans},
+    widgets::{Block, Borders, Paragraph, Wrap, List, ListItem},
+    Terminal,
+};
+
+mod input;
+use self::input::InputEvents;
+
+mod metrics;
+use self::metrics::{ClientState, MetricData};
+
+mod selector;
+use self::selector::Selector;
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let stdout = io::stdout().into_raw_mode()?;
+    let stdout = MouseTerminal::from(stdout);
+    let stdout = AlternateScreen::from(stdout);
+    let backend = TermionBackend::new(stdout);
+    let mut terminal = Terminal::new(backend)?;
+
+    let mut events = InputEvents::new();
+    let client = metrics::Client::new("127.0.0.1:5000".to_string());
+    let mut selector = Selector::new();
+
+    loop {
+        terminal.draw(|f| {
+            let chunks = Layout::default()
+                .direction(Direction::Vertical)
+                .margin(1)
+                .constraints(
+                    [
+                        Constraint::Length(4),
+                        Constraint::Percentage(90)
+                    ].as_ref()
+                )
+                .split(f.size());
+
+            let current_dt = Local::now().format(" (%Y/%m/%d %I:%M:%S %p)").to_string();
+            let client_state = match client.state() {
+                ClientState::Disconnected(s) => {
+                    let mut spans = vec![
+                        Span::raw("state: "),
+                        Span::styled("disconnected", Style::default().fg(Color::Red)),
+                    ];
+
+                    if let Some(s) = s {
+                        spans.push(Span::raw(" "));
+                        spans.push(Span::raw(s));
+                    }
+
+                    Spans::from(spans)
+                },
+                ClientState::Connected => Spans::from(vec![
+                    Span::raw("state: "),
+                    Span::styled("connected", Style::default().fg(Color::Green)),
+                ]),
+            };
+
+            let header_block = Block::default()
+                .title(vec![
+                    Span::styled("metrics-observer", Style::default().add_modifier(Modifier::BOLD)),
+                    Span::raw(current_dt),
+                ])
+                .borders(Borders::ALL);
+
+            let text = vec![
+                client_state.into(),
+                Spans::from(vec![
+                    Span::styled("controls: ", Style::default().add_modifier(Modifier::BOLD)),
+                    Span::raw("up/down = scroll, q = quit"),
+                ]),
+            ];
+            let header = Paragraph::new(text)
+                .block(header_block)
+                .wrap(Wrap { trim: true });
+
+            f.render_widget(header, chunks[0]);
+
+            // Knock 5 off the line width to account for 3-character highlight symbol + borders.
+            let line_width = chunks[1].width.saturating_sub(6) as usize;
+            let items = client.with_metrics(|metrics| {
+                let mut items = Vec::new();
+                for (key, value) in metrics.iter() {
+                    let inner_key = key.key();
+                    let name = inner_key.name();
+                    let labels = inner_key.labels().map(|label| format!("{} = {}", label.key(), label.value())).collect::<Vec<_>>();
+                    let display_name = if labels.is_empty() {
+                        name.to_string()
+                    } else {
+                        format!("{} [{}]", name, labels.join(", "))
+                    };
+
+                    let display_value = match value {
+                        MetricData::Counter(value) => format!("total: {}", value),
+                        MetricData::Gauge(value) => format!("current: {}", value),
+                        MetricData::Histogram(value) => {
+                            let min = value.min();
+                            let max = value.max();
+                            let p50 = value.value_at_quantile(0.5);
+                            let p99 = value.value_at_quantile(0.99);
+                            let p999 = value.value_at_quantile(0.999);
+
+                            format!("min: {} p50: {} p99: {} p999: {} max: {}",
+                                min, p50, p99, p999, max)
+                        },
+                    };
+
+                    let name_length = display_name.chars().count();
+                    let value_length = display_value.chars().count();
+                    let space = line_width.saturating_sub(name_length).saturating_sub(value_length);
+
+                    let display = format!("{}{}{}", display_name, " ".repeat(space), display_value);
+                    items.push(ListItem::new(display));
+                }
+                items
+            });
+            selector.set_length(items.len());
+
+            let metrics_block = Block::default()
+                .title("observed metrics")
+                .borders(Borders::ALL);
+
+            let metrics = List::new(items)
+                .block(metrics_block)
+                .highlight_symbol(">> ");
+            
+            f.render_stateful_widget(metrics, chunks[1], selector.state());
+        })?;
+
+        // Poll the event queue for input events.  `next` will only block for 1 second,
+        // so our screen is never stale by more than 1 second.
+        if let Some(input) = events.next()? {
+            match input {
+                Key::Char('q') => break,
+                Key::Up => selector.previous(),
+                Key::Down => selector.next(),
+                Key::PageUp => selector.top(),
+                Key::PageDown => selector.bottom(),
+                _ => {},
+            }
+        }
+    }
+
+    Ok(())
+}
\ No newline at end of file
diff --git a/metrics-observer/src/metrics.rs b/metrics-observer/src/metrics.rs
new file mode 100644
index 0000000..0d0a4b2
--- /dev/null
+++ b/metrics-observer/src/metrics.rs
@@ -0,0 +1,221 @@
+use std::collections::HashMap;
+use std::net::TcpStream;
+use std::time::Duration;
+use std::thread;
+use std::net::ToSocketAddrs;
+use std::sync::{Arc, Mutex, RwLock};
+use std::io::Read;
+
+use bytes::{BufMut, BytesMut};
+use prost::Message;
+use hdrhistogram::Histogram;
+
+use metrics::{Label, KeyData};
+use metrics_util::{CompositeKey, MetricKind};
+
+mod proto {
+    include!(concat!(env!("OUT_DIR"), "/event.proto.rs"));
+}
+
+#[derive(Clone)]
+pub enum ClientState {
+    Disconnected(Option<String>),
+    Connected,
+}
+
+pub enum MetricData {
+    Counter(u64),
+    Gauge(f64),
+    Histogram(Histogram<u64>),
+}
+
+pub struct Client {
+    state: Arc<Mutex<ClientState>>,
+    metrics: Arc<RwLock<HashMap<CompositeKey, MetricData>>>,
+    handle: thread::JoinHandle<()>,
+}
+
+impl Client {
+    pub fn new(addr: String) -> Client {
+        let state = Arc::new(Mutex::new(ClientState::Disconnected(None)));
+        let metrics = Arc::new(RwLock::new(HashMap::new()));
+        let handle = {
+            let state = state.clone();
+            let metrics = metrics.clone();
+            thread::spawn(move || {
+                let mut runner = Runner::new(addr, state, metrics);
+                runner.run();
+            })
+        };
+
+        Client {
+            state,
+            metrics,
+            handle,
+        }
+    }
+
+    pub fn state(&self) -> ClientState {
+        self.state.lock().unwrap().clone()
+    }
+
+    pub fn with_metrics<F, T>(&self, f: F) -> T
+    where
+        F: FnOnce(&HashMap<CompositeKey, MetricData>) -> T,
+    {
+        let handle = self.metrics.read().unwrap();
+        f(&handle)
+    }
+}
+
+enum RunnerState {
+    Disconnected,
+    ErrorBackoff(&'static str, Duration),
+    Connected(TcpStream),
+}
+
+struct Runner {
+    state: RunnerState,
+    addr: String,
+    client_state: Arc<Mutex<ClientState>>,
+    metrics: Arc<RwLock<HashMap<CompositeKey, MetricData>>>,
+}
+
+impl Runner {
+    pub fn new(
+        addr: String,
+        state: Arc<Mutex<ClientState>>,
+        metrics: Arc<RwLock<HashMap<CompositeKey, MetricData>>>,
+    ) -> Runner {
+        Runner {
+            state: RunnerState::Disconnected,
+            addr,
+            client_state: state,
+            metrics,
+        }
+    }
+
+    /*pub fn run(&mut self) {
+        let mut metrics = self.metrics.write().unwrap();
+
+        metrics.insert(("test_counter".into(), Vec::new()), MetricData::Counter(42));
+        metrics.insert(
+            ("test_counter_two".into(), vec!["endpoint = http".to_string()]),
+            MetricData::Counter(42)
+        );
+        metrics.insert(("test_gauge".into(), Vec::new()), MetricData::Gauge(-666));
+        
+        let mut histogram = Histogram::<u64>::new(3)
+            .expect("failed to create histogram");
+        for i in 1..100 {
+            histogram.record(i).expect("failed to record value");
+        }
+        metrics.insert(("test_histogram".into(), Vec::new()), MetricData::Histogram(histogram));
+    }*/
+
+    pub fn run(&mut self) {
+        loop {
+            let next = match self.state {
+                RunnerState::Disconnected => {
+                    // Just reset the client state here to be sure.
+                    {
+                        let mut state = self.client_state.lock().unwrap();
+                        *state = ClientState::Disconnected(None);
+                    }
+                     
+                    // Try to connect to our target and transition into Connected.
+                    let addr = match self.addr.to_socket_addrs() {
+                        Ok(mut addrs) => match addrs.next() {
+                            Some(addr) => addr,
+                            None => {
+                                let mut state = self.client_state.lock().unwrap();
+                                *state = ClientState::Disconnected(Some("failed to resolve specified host".to_string()));
+                                break;
+                            }
+                        }
+                        Err(_) => {
+                            let mut state = self.client_state.lock().unwrap();
+                            *state = ClientState::Disconnected(Some("failed to resolve specified host".to_string()));
+                            break;
+                        }
+                    };
+                    match TcpStream::connect_timeout(&addr, Duration::from_secs(3)) {
+                        Ok(stream) => RunnerState::Connected(stream),
+                        Err(_) => {
+                            RunnerState::ErrorBackoff("error while connecting", Duration::from_secs(3))
+                        }
+                    }
+                },
+                RunnerState::ErrorBackoff(msg, dur) => {
+                    {
+                        let mut state = self.client_state.lock().unwrap();
+                        *state = ClientState::Disconnected(Some(format!("{}, retrying in {} seconds...", msg, dur.as_secs())));
+                    }
+                    thread::sleep(dur);
+                    RunnerState::Disconnected
+                },
+                RunnerState::Connected(ref mut stream) => {
+                    {
+                        let mut state = self.client_state.lock().unwrap();
+                        *state = ClientState::Connected;
+                    }
+
+                    let mut buf = BytesMut::new();
+                    let mut rbuf = [0u8; 1024];
+                
+                    loop {
+                        match stream.read(&mut rbuf[..]) {
+                            Ok(0) => break,
+                            Ok(n) => buf.put_slice(&rbuf[..n]),
+                            Err(e) => eprintln!("read error: {:?}", e),
+                        };
+                
+                        match proto::Metric::decode_length_delimited(&mut buf) {
+                            Err(e) => eprintln!("decode error: {:?}", e),
+                            Ok(msg) => {
+                                let mut labels_raw = msg.labels.into_iter().collect::<Vec<_>>();
+                                labels_raw.sort_by(|a, b| a.0.cmp(&b.0));
+                                let labels = labels_raw.into_iter().map(|(k, v)| Label::new(k, v)).collect::<Vec<_>>();
+                                let key_data: KeyData = (msg.name, labels).into();
+
+                                match msg.value.expect("no metric value") {
+                                    proto::metric::Value::Counter(value) => {
+                                        let key = CompositeKey::new(MetricKind::Counter, key_data.into());
+                                        let mut metrics = self.metrics.write().unwrap();
+                                        let counter = metrics.entry(key).or_insert_with(|| MetricData::Counter(0));
+                                        if let MetricData::Counter(inner) = counter {
+                                            *inner += value.value;
+                                        }
+                                    },
+                                    proto::metric::Value::Gauge(value) => {
+                                        let key = CompositeKey::new(MetricKind::Gauge, key_data.into());
+                                        let mut metrics = self.metrics.write().unwrap();
+                                        let gauge = metrics.entry(key).or_insert_with(|| MetricData::Gauge(0.0));
+                                        if let MetricData::Gauge(inner) = gauge {
+                                            *inner = value.value;
+                                        }
+                                    },
+                                    proto::metric::Value::Histogram(value) => {
+                                        let key = CompositeKey::new(MetricKind::Histogram, key_data.into());
+                                        let mut metrics = self.metrics.write().unwrap();
+                                        let histogram = metrics.entry(key).or_insert_with(|| {
+                                            let histogram = Histogram::new(3).expect("failed to create histogram");
+                                            MetricData::Histogram(histogram)
+                                        });
+
+                                        if let MetricData::Histogram(inner) = histogram {
+                                            inner.record(value.value).expect("failed to record value to histogram");
+                                        }
+                                    },
+                                }
+                            },
+                        }
+                    }
+
+                    RunnerState::ErrorBackoff("error while observing", Duration::from_secs(3))
+                }
+            };
+            self.state = next;
+        }
+    }
+}
\ No newline at end of file
diff --git a/metrics-observer/src/selector.rs b/metrics-observer/src/selector.rs
new file mode 100644
index 0000000..0b4ca3c
--- /dev/null
+++ b/metrics-observer/src/selector.rs
@@ -0,0 +1,58 @@
+use tui::widgets::ListState;
+
+pub struct Selector(usize, ListState);
+
+impl Selector {
+    pub fn new() -> Selector {
+        let mut state = ListState::default();
+        state.select(Some(0));
+        Selector(0, state)
+    }
+
+    pub fn set_length(&mut self, len: usize) {
+        if len < self.0 {
+            self.1.select(Some(0));
+        }
+        self.0 = len;
+    }
+
+    pub fn state(&mut self) -> &mut ListState {
+        &mut self.1
+    }
+
+    pub fn top(&mut self) {
+        self.1.select(Some(0));
+    }
+
+    pub fn bottom(&mut self) {
+        self.1.select(Some(self.0 - 1));
+    }
+
+    pub fn next(&mut self) {
+        let i = match self.1.selected() {
+            Some(i) => {
+                if i >= self.0 - 1 {
+                    0
+                } else {
+                    i + 1
+                }
+            }
+            None => 0,
+        };
+        self.1.select(Some(i));
+    }
+
+    pub fn previous(&mut self) {
+        let i = match self.1.selected() {
+            Some(i) => {
+                if i == 0 {
+                    self.0 - 1
+                } else {
+                    i - 1
+                }
+            }
+            None => 0,
+        };
+        self.1.select(Some(i));
+    }
+}
\ No newline at end of file