diff --git a/README.md b/README.md
index 049eaa81..6c6d040a 100644
--- a/README.md
+++ b/README.md
@@ -186,9 +186,19 @@ docker run -it --security-opt="apparmor=unconfined" --cap-add=SYS_PTRACE --pid=h
 ### Generate flamegraphs from traces
 ```bash
 sudo php ./php-profiler inspector:trace -p <pid of the target process or thread> >traces
-./tools/stackcollapse-phpspy/stackcollapse-phpspy.pl <traces | ./tools/flamegraph/flamegraph.pl >flame.svg
+./php-profiler converter:flamegraph <traces >flame.svg
 ```
 
+### Generate the [speedscope](https://github.com/jlfwong/speedscope) format from phpspy compatible traces
+```bash
+sudo php ./php-profiler inspector:trace -p <pid of the target process or thread> >traces
+./php-profiler converter:speedscope <traces >profile.speedscope.json
+speedscope profile.speedscope.json
+```
+
+See [#101](https://github.com/sj-i/php-profiler/pull/101).
+
+
 # LICENSE
 - MIT (mostly)
 - Some C headers defining internal structures are extracted from php-src. They are licensed under the zend engine license. See src/Lib/PhpInternals/Headers . So here are the words required by the zend engine license.
diff --git a/src/Command/Converter/SpeedscopeCommand.php b/src/Command/Converter/SpeedscopeCommand.php
new file mode 100644
index 00000000..85735bf3
--- /dev/null
+++ b/src/Command/Converter/SpeedscopeCommand.php
@@ -0,0 +1,127 @@
+<?php
+
+/**
+ * This file is part of the sj-i/php-profiler package.
+ *
+ * (c) sji <sji@sj-i.dev>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+declare(strict_types=1);
+
+namespace PhpProfiler\Command\Converter;
+
+use PhpCast\Cast;
+use PhpProfiler\Lib\PhpInternals\Opcodes\OpcodeV80;
+use PhpProfiler\Lib\PhpInternals\Types\Zend\Opline;
+use PhpProfiler\Lib\PhpProcessReader\CallFrame;
+use PhpProfiler\Lib\PhpProcessReader\CallTrace;
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Output\OutputInterface;
+
+final class SpeedscopeCommand extends Command
+{
+    public function configure(): void
+    {
+        $this->setName('converter:speedscope')
+            ->setDescription('convert traces to the speedscope file format')
+        ;
+    }
+
+    public function execute(InputInterface $input, OutputInterface $output): int
+    {
+        $output->write(
+            json_encode(
+                $this->collectFrames(
+                    $this->getTraceIterator(STDIN)
+                )
+            )
+        );
+        return 0;
+    }
+
+    /**
+     * @param resource $fp
+     * @return iterable<int, CallTrace>
+     */
+    private function getTraceIterator($fp): iterable
+    {
+        $buffer = [];
+        while (($line = fgets($fp)) !== false) {
+            $line = trim($line);
+            if ($line !== '') {
+                $buffer[] = $line;
+                continue;
+            }
+            yield $this->parsePhpSpyCompatible($buffer);
+            $buffer = [];
+        }
+    }
+
+    /** @param string[] $buffer */
+    private function parsePhpSpyCompatible(array $buffer): CallTrace
+    {
+        $frames = [];
+        foreach ($buffer as $line_buffer) {
+            $result = explode(' ', $line_buffer);
+            [$depth, $name, $file_line] = $result;
+            if ($depth === '#') { // comment
+                continue;
+            }
+            [$file, $line] = explode(':', $file_line);
+            $frames[] = new CallFrame(
+                '',
+                $name,
+                $file,
+                new Opline(0, 0, 0, 0, Cast::toInt($line), new OpcodeV80(0), 0, 0, 0),
+            );
+        }
+        return new CallTrace(...$frames);
+    }
+
+    /** @param iterable<CallTrace> $call_frames */
+    private function collectFrames(iterable $call_frames): array
+    {
+        $mapper = fn (array $value): string => \json_encode($value);
+        $trace_map = [];
+        $result_frames = [];
+        $sampled_stacks = [];
+        $counter = 0;
+        foreach ($call_frames as $frames) {
+            $sampled_stack = [];
+            foreach ($frames->call_frames as $call_frame) {
+                    $frame = [
+                    'name' => $call_frame->getFullyQualifiedFunctionName(),
+                    'file' => $call_frame->file_name,
+                    'line' => $call_frame->getLineno(),
+                    ];
+                    $mapper_key = $mapper($frame);
+                    if (!isset($trace_map[$mapper_key])) {
+                        $result_frames[] = $frame;
+                        $trace_map[$mapper_key] = array_key_last($result_frames);
+                    }
+                    $sampled_stack[] = $trace_map[$mapper_key];
+            }
+            $sampled_stacks[] = \array_reverse($sampled_stack);
+            $counter++;
+        }
+        return [
+            "\$schema" => "https://www.speedscope.app/file-format-schema.json",
+            'shared' => [
+                'frames' => $result_frames,
+            ],
+            'profiles' => [[
+                'type' => 'sampled',
+                'name' => 'test',
+                'unit' => 'none',
+                'startValue' => 0,
+                'endValue' => $counter,
+                'samples' => $sampled_stacks,
+                'weights' => array_fill(0, count($sampled_stacks), 1),
+            ]]
+        ];
+    }
+}